. 2023 Dec 11;13:21962. doi: 10.1038/s41598-023-48179-1

Table 1.

General characteristic of the studies.

Study	Study design	Participants	Intervention	Dosage	Outcome measurement instrument	Results
Davis and Sinning (1987)³³ United States of America	Quasi- experimental	IG1: 6 men with DS. Age: 20–38.2 years. IQ ranging 32–41 IG2: 6 men with mental disabilities without DS. Age 18.5–36.2 years. IQ ranging 33–57 CG: 6 undergraduate and postgraduate students. Age: 19–24.3 years. Above average IQ	IG1 AND IG2: Strength training under the supervision of graduates and graduates in physical education who were instructed in the procedures. Individual records of weight, series and repetitions were set CG: They exercised individually and recorded their own progress	Mode: bench press, triceps curls, and biceps curls with free weight Intensity: 6–8 repetitions. The amount of weight for each particular set was progressively increased as the subjects were able to exceed 8 repetitions Duration: 8 weeks Frequency: 3 times a week	Elbow flexor strength: Maximum voluntary contraction: supine, right arm in 90° elbow flexion, exert 2 maximum efforts against immovable resistance. In the same position, exert a force for 5 s against a series of loads ranging from 5 lb to approximately 90% of the maximum effort measured Electromyography: Electrodes are placed on the flexor muscle group at the elbow (biceps brachii). Integrated EMG and torque measurements of the elbow flexor muscle group were recorded simultaneously during maximal effort and step loading procedures	Only half of the subjects increased their maximum voluntary contraction as a result of the training, but there were no significant differences between groups P > 0.05 As expected, the post measurements of the group without disabilities experienced more improvement than the other two groups with disabilities, being statistically significant. p < 0.001
Carmeli et al. 2002¹⁰ Israel	Experimental	26 older adults aged 57–65 years Mild mental retardation IQ ranging 56–75 according to the Stanford Binet scale IG: 16 participants (10 women, 6 men) CG: 10 participants (6 women, 4 men)	IG: Aerobic exercise with treadmill walking Participants walked only between 9:30 and 11:30 am indoors under controlled conditions (23 °C, 40% humidity) CG: They were instructed not to change their daily activity level	Mode: Endless treadmill walk Intensity: Low resistance with 0% incline Intensity: Speed below the threshold for breathlessness but as fast as they could comfortably tolerate Frequency: 3 times/week Duration: 25 consecutive weeks. They initially walked for 10–15 min. The duration was gradually increased up to 45 min according to tolerance	Dynamic balance and gait speed: - Timed up and go Muscle strength: - Flexion (hamstrings) and extension (Quadriceps) of the knee in the isokinetic system (Biodex dynamometer) at speeds of 60°/s and 120°/s Data were collected for peak torque (ft/lb) (highest individual value of three peak efforts), peak torque percentage of body weight (ft/lb/kg), and average power (watts)	Timed up and go: IG: 25.9 ± 3 s. CG: 29.1 ± 3 s. Significant improvements between groups p < 0.05 Muscle strength: Significant differences are found in all three tests (maximum torque, % maximum torque of body weight and average power) of hamstrings and quadriceps in both men and women p < 0.01
Rimmer et al. (2004)¹⁶ United States of America	Experimental	52 adults with DS. Mean age 39.4 ± 6.4 IG: 30 participants CG: 22 participants. without intervention	IG: Cardio and strength exercises Exercise classes were supervised by a full-time registered clinical exercise physiologist and two assistants	CARDIOVASCULAR TRAINING Mode: Recumbent stepper, stationary cycle (recumbent and upright), treadmill and elliptical Duration: 15–20 min the first 2 weeks, 20–30 min the third and fourth weeks, 30 min from the fifth week onward for 12 weeks Intensity: 50%–70% of VO2 max. Monitored with cardiac monitors STRENGTH TRAINING Mode: seated bench and leg press, seated leg curl, triceps curl, seated shoulder press, seated row, push-up Duration: 15–20 min Intensity: initially 70% of 1-RM for a set of 10–20 reps. When participants were able to complete 20 reps for 2 consecutive sessions with proper lifting technique, the weight was increased by 10% of their 1-RM	Strength: 1-RM protocol according to the ACSM Leg press Chest press Grip Strength: Manual dynamometry	Leg Press: IG: 320 lb (87) 145.1 kg (39.4). CG: 208 lb (97) 94.3 kg (43.9). Significant differences p < 0.0001 Chest Press: IG: 100.7 lb (44.9) 45.6 kg (20.3). CG: 59.9 lb (33.6) 27.1 kg (15.2). Significant differences p < 0.0001 Dynamometry: IG: Right hand 22.0 (8.1); Left hand 21.6 (8.7) CG: Right hand 19.0 (7.7); Left hand 17.8 (7.0) Nonsignificant differences neither on the left nor on the right side p > 0.05
Tsimaras and Fotiadou (2004)³⁰ Greece	Quasi-experimental	25 adults with DS all from the Center of Professional Learning of Thessaloniki IG: 15 participants. IQ range, 45–60. Age, 24.5 ± 3.9 years CG: 10 participants. (IQ range, 45– 59. Age 24.7 ± 2.7 years	IG: a 12-week Cardio and strength training	Mode: walking, slow running, and free gymnastic activities that mobilize large muscle groups (10 min) 15–20 min of training program activities: 1. Two-foot ankle hop. 2. Single-foot side-to side ankle hop. 3. Tuck jump with knees up. 4. Tuck jump with heel kick. 5. Standing long jump. 6. Standing jump over barrier. 7. Single leg hops. 8. Double leg hops. 9. Standing on 1 foot. 10. Rocking boats. 11. Walking on line. 12. Walking across 30-cm-wide balance beam. 13. Walking across 20-cm-wide balance beam. 14. Walking across 10-cm-wide balance beam Finally, 5-min recovery period Frequency: 3 times per week, Duration: 30–35 min/sesion	Peak torque of knee extension and flexion: Cybex II isokinetic dynamometer Isokinetic muscle endurance of quadriceps muscles: after 25 repeated maximum efforts at an angular velocity of 180° , and it was defined by the percentage of decline from the peak torque Dynamic balance ability: balance deck. Number of seconds the subject could remain standing on the platform of the stabilometer in durations of 30-, 45-, and 60-s intervals	Isokinetic peak torque of anterior (300, 180, 120° p < 0.001, 60°p < 0.01) and posterior (300, 180, 120° p < 0.01, 60° p < 0.01) femoral muscles significantly improved for the experiment group The isokinetic endurance: it showed a significant improvement (p < 0.01) after participation in the training program Dynamic balance ability: was significantly improved for the experiment group (30 s p < 0.01, 45 s and 60 s p < 0.001, No significant differences were found in any of the measurements for the control group For the initial and final measurements, no statistically significant differences were found between the 2 groups
Aguiar et al. (2008)²⁷ Brazil	Quasi-experimental	IG: 21 men Age: 23.3 ± 2.1	Monitored aerobic exercise of adapted judo training for 16 weeks	Mode: Adapted Judo Intensity: Lactate threshold Frequency: 3 times/week Duration: 50 min/session	Gross motor skills: GMFM-88	The judo training program significantly (P < 0.05) improved the GMFM-88 index of young adults with DS
Shields et al. (2008)⁸ Australia	Experimental	20 adults. Age: 26.8 ± 7.8 years 13 men, 7 women IG: 9 participants CG: 11 participants 8 of the 20 participants worked at least 1 day/week in manual-type jobs (packing confectionery boxes, sorting and cutting clothes, and assembling car parts)	IG: Group progressive resistance training in a supervised community gym. The trainer kept a record for each participant of the number of repetitions and sets and the weight lifted/exercised in each session. Participants completed the program in a group, supervised by 2 accredited fitness trainers. Each trainer supervised the training of a subgroup of 2–3 participants CG: Continued with usual activities (work, free time, and leisure)	Mode: Progressive resistance training with machines: - Shoulder press - Seated chest press - Seated rowing - Seated leg press - Knee extension - Seated calf raise Intensity: Increased when 2 sets of 12 reps per exercise could be completed Volume: 2–3 sets of 10–12 reps per exercise to failure Frequency: 2 times a week Duration: 10 weeks Density: 2-min rest between sets	Muscle performance: - 1 RM: Chest press and leg press - Muscular resistance: repetitions of chest and leg press with 50% of 1RM Physical function: - Timed up and down stairs test - Grocery shelving task: Get up from a chair and take 2 bags of groceries to a bench located 2 m away. Each bag contains 10 items (410 g each, total weight of each bag 4.1 kg). Then they have to take the items out of the bag and stack them on a shelf at shoulder height	1 RM Chest Press: IG: 44.9 ± 15.2 kg. CG: 31.6 ± 13.3 kg 1 RM Leg Press: IG: 96.2 ± 31.6 kg. CG: 82.2 ± 19.7 kg Rep Chest Press: IG: 25.9 ± 8.3. CG 17.5 ± 9.5 Rep Leg Press: IG: 46.8 ± 37.1. CG: 49.4 ± 27.6 Timed up and down stairs: IG: 14.4 ± 3.4 s. CG: 18.7 ± 6.5 s Grocery shelving task: IG: 67.5 ± 33.4 s. CG: pre 122.8 ± 84.0 s; post 110.7 ± 66.4 s Significant differences between groups in 1-RM chest press (P 0.08), chest press repetitions (P 0.002), and leg press repetitions (P 0.039) No significant differences between groups in the leg press 1RM test (P 0.90), timed up and go (P 0.12) or grocery shelving task test (P 0.11)
Cowley et al. 2011⁹ United States of America	Quasi- experimental	30 adults with mild intellectual disabilities. Age: 28 ± 8 years IG: 9 men and 10 women CG: 11 participants. 8 men and 3 women	IG: progressive resistance training Each participant worked one on one with a professional who supervised all the training sessions CG: Maintained normal daily activities	Mode: Leg extension, leg curl, leg press, shoulder press, chest press, bicep curl, and tricep curl exercises performed on exercise machines Intensity: 3 sets of 8–10 reps per exercise. The weight lifted by the subject was recorded during the training period and progressively increased to constantly overload the muscle Frequency: 2 days per week Duration: 10 weeks	Isometric and isokinetic strength of knee extensors and flexors: Biodex System 3 dynamometer - Maximum isometric peak torque: 3 series of 3 maximum contractions with knee extensors and flexors at a joint angle of 45°, 60°, and 75° with 3 min interval between series - Maximum isokinetic peak torque: 3 series of 5 maximum contractions with knee extensors and flexors at 60°/s with 3 min interval between series Functional tasks of daily life: - Time to get up from a chair at different heights (30, 38, or 43 cm) as quickly as possible to an upright position with trunk and legs straight, keeping arms crossed over the chest - Gait speed: Walk 7.62 m - Go up and down 10 steps as fast as possible without using the support handrail and alternating feet and then go down	Isometric flexor strength: Significant differences between groups P < 0.05 in the three degrees of movement (45°, 60°, and 75°) Isometric strength extensors: Significant differences in the IG in the three degrees of movement P < 0.05 Flexors and extensors isokinetic strength Significant differences in the IG P < 0.05 Getting up from a chair at different heights: No significant differences P > 0.05 in any of the chair heights (30 cm, 38 cm, 43 cm) or in the 5 repetitions 10-step ascent and descent: Significant differences in the IG P < 0.05 in both tests. IG Ascent: .83 SD 1.19. CG: 5.10 SD 1.19. GI descent: 4.38 SD 1.19. CG: 6.23 SD 2.80 Gait speed: IG: 1.72 SD 0.20. CG: 1.71 SD 0.24. No significant differences P > 0.05
Mendonca et al. (2011)¹⁵ Portugal	Quasi- experimental	IG1: 13 participants (10 men, 3 women) with DS. Age: 36.5 ± 5.5 years IG2: 12 participants (9 men, 3 women) without disabilities. Age: 38.7 ± 8.3 years	Combined resistance and strength exercise training The exercise sessions were supervised by an exercise physiologist and an assistant	ENDURANCE TRAINING Mode: Walk or run on a treadmill Intensity: target heart rate compatible with 65% (first three weeks) at 85% of VO2peak. Monitored with fc/participant clock Duration: 30 min. 12 weeks Frequency: 3 days/week STRENGTH TRAINING Mode: repeating a set of 9 exercises twice with < 30 s of rest between them. Train with leg press, chest and shoulder press, vertical pull, lower back, leg extension, bicep curl, and tricep curl. In addition, 1 set of 15 repetitions of abdominal push-ups in each rotation Intensity: 10% increase in 12-RM load when participants were able to complete 14 reps for 2 consecutive sessions with proper technique Frequency: 2 days/week	Muscle strength: 12-RM protocol on variable resistance machines - Leg press - Chest press - Vertical traction - Lower back - Leg extension Each participant was asked to perform 15 reps with relatively light resistance followed by 30 s of recovery. Resistance was then increased, and each participant performed a maximum of 5 sets of 12 repetitions until the 12-RM was reached. The recovery period between sets was exactly 2 min, and increments of 2.5–5 kg were used as each participant approached fatigue. The 12-RM was defined as the maximum load lifted through a full range of motion for a total of 12 repetitions. For most participants, the 12-RM was determined in 3–4 attempts	Leg Press: IG1: 110.2 ± 52.6. IG2: 171.3 ± 56.5 Chest Press: IG1: 35.3 ± 12.2. IG2: 51.3 ± 21.0 Vertical Traction: IG1: 39.2 ± 14.1. IG2: 59.4 ± 15.3 Lower Back: IG1: 35.6 ± 7.4. IG2: 51.9 ± 19.3 Leg Extension: IG1: 30.1 ± 10.3. IG2: 52.7 ± 17.6 Participants with Down syndrome showed lower muscle strength than participants without disabilities in all dynamic exercises, both before and after training Training was highly efficient in obtaining generalized improvements for 12-RM in both groups (P < 0.05). The magnitude of these improvements was similar between participants with and without Down syndrome
Boer and Moss, (2016)⁵ South Africa	Experimental	42 adults. Age 33.8 ± 8.6 (25 men, 17 women) IG1: 13 participants IG2: 13 participants CG: 16 participants	IG1: Continuous aerobic training (CAT) on a bicycle or treadmill IG2: Interval training (IT) with 10–30-s sprints on a bike or treadmill The two IGs performed the intervention under the supervision of a licensed sport scientist and exercise physiologist in a 2:6 (professional:participants) ratio CG: No intervention	Duration: 12 weeks. 30-min sessions the first six weeks (5-min warm-up, 20-min central act, 5-min cool down), the last six weeks’ sessions were increased by 5 min for the central activity Intensity: Warm up and cool down at 4 km/h Frequency: 3 times/week IG1: CAT - Mode: Continuous aerobic training by bicycle (50%) or treadmill (50%) - Central act intensity: first six weeks 70%–80% VO2peak, last 6 weeks 85% VO2peak IG2: IT - Mode: Interval aerobic training on a bicycle (50%) or treadmill (50%) - Intensity: 10–30-s max sprints with 90-s low cadence, low intensity gait, or bike	Grip strength: - Manual dynamometry in the dominant hand Lower Body Strength: - Sit-to-stand test Agility and dynamic balance: - 8-ft up and go Aerobic capacity and functional ability: - 6MWD	Grip strength: CAT: 26.1 kg (7.9). IT: 29.9 kg (8.9). CG: 25.5 kg (9.1). No significant differences between groups P = 0.57 Lower Body Strength: CAT: 15.2 (1.8). IT: 15.5 (1.8). CG: 13.3 (2.3). Significant improvements between groups P = 0.01 and only in the CAT group compared to the control group (P < 0.05) Agility and balance: CAT: 4.8 s (0.9). IT: 4.9 s (1.1). CG: 6.2 s (1.3). Significant improvements between groups P = 0.03 and only in the CAT group compared to the control group (P < 0.05) Aerobic capacity and functional ability: CAT: 563.2 m (74.9). IT: 562.6 m (81.7). CG: 495.9 m (85.2). Significant improvements between groups P = 0.01 and only in the CAT group compared to the control group (P < 0.05)
Silva et al. (2017)³² Portugal	Experimental	27 adults aged 18–60 years IG: 14 participants CG: 13 participants	IG: Wii-based exercise program that included training games for aerobic endurance, balance, and isometric strength CG: They completed their usual daily activities (usual treatment) at their occupational center, such as rehabilitation, life skills training, and art-related activities	Mode: Aerobic exercise through a Wii-based exercise program. Individual sessions or with another participant (half of the sessions in each format) Frequency: 3 sessions per week Duration: 2 months	Physical aptitude: Eurofit test battery: - Limb movement speed (Plate Tapping Test) - Static arm strength (Handgrip Test) - Running speed and agility (Shuttle Run) - Balance (Flamingo Balance) - Flexibility (Sit and Reach) - Explosive power of the legs (Standing Broad) - Trunk Strength (30-s Sit-ups) - Muscular resistance (Bent Arm Hang) Functional mobility: - Timed Up and Go - Response speed subtest of the Bruininks–Oseretsky Motor Competence Test First Edition Motor skills: - Beanbag Overhead	Significant improvements in the GI in the Handgrip test (IG: 25.42 (5.53). CG: 23.92 (6.45) P 0,025), in the sit and reach (IG: 36.92 (7.22). CG: 29.46 (10.53) P 0,014), in the standing broad (IG: 99.33 (29.49). CG: 90.69 (35.20) P < 0,001) and in the Bruininks–Oseretsky First Edition test (IG: 4.67 (2.81). CG: 4.77 (2.17) P 0.028) Significant differences between groups were identified in the plate tapping test (P 0.045), shuttle run (P 0.014), sit and reach (P 0.027), standing broad (P 0.003), 30-s sit-ups (P 0.040) and timed up and go (P 0.049) No significant differences in the handgrip test (P 0.837), flamingo balance (P 0.477), bent arm hang (P 0.086), Bruininks–Oseretsky First Edition (P 0.265), neither in the beanbag overhead nor in the hand right P 0.150 nor in the left P 0.083
Boer and de Beer (2019)² South Africa	Quasi- experimental	23 adults. Age 31.4 ± 7.4 years IG: 13 participants (8 men, 5 women) CG: 10 participants (5 men, 5 women)	IG: Aerobic exercise in aquatic environment. Aquatic training. Sessions controlled and monitored by test instructors and senior Human Movement Sciences students (approximately one test instructor per two participants) CG: No intervention additional to ADLs	Mode: Aquatic training with arm circle exercises, lateral twists, walk in place, run in place, water scoops, lateral leg raises, back flutter kick, stomach flutter kick, jumping jacks, knee twists, side shift, squat jumps, lunge jumps, and longer jog, 1.4-m-deep pool Duration: 6 weeks, 35 min the first 3 weeks, 45 min the last 3 weeks. Consider a 3-min warm up and 2-min cool down Frequency: 3 times/week	Static Balance: - Balance on one leg Dynamic Balance: - Walk on a balance beam Functional fitness: - 6MWD - 8-ft up and go Muscular strength: - Sit-to-stand test -Curl‐up modified -Isometric push-up	Static Balance: No significant differences P > 0.05 in the static balance IG: 6.6 (3.5). CG: 5.1 (3.6), nor dynamic IG: 5.6 (0.8). CG: 4.6 (2.1) Functional fitness: Significant differences between groups P < 0.05 for the 6MWD test: IG: 602.1(98.7). CG: 519. 9 (111.9). No significant differences P > 0.05 in the 8-ft up and go test: IG: .3 (0.9). CG: .5 (0.9) Muscle strength: Significant differences between groups P < 0.05 for sit-to-stand test GI: 14.5 (2.2). CG: 13.0 (1.8) and modified curl up GI: 37.9 (30.1). CG: 20.0 (28.3). Nonsignificant differences P > 0.05 for isometric push-up IG: 82.2 (50.9). CG: 36.5 (32.5)
Skiba et al. (2019)¹³ Polonia	Experimental	22 adults aged 25– 40 years, with moderate intellectual disability (IQ: 36–51). 11 men, 11 women IG: 11 participants. CG: 11 participants	IG: Aerobic exercise with Nordic walking training program. The exercises were performed by a physiotherapist, who was a qualified Nordic walking instructor CG: Did not undergo any training	Mode: Brisk Nordic walking Intensity: Progressed over the course of the training sessions Frequency: 3 times a week Duration: 45 min	Spatiotemporal parameters (step and stride length and speed) and maximum values of angles in the ankle, knee, hip, and shoulder joints in different phases of gait: Using the Vicon 250 Optoelectronic System for Three-Dimensional Motion Analysis	Gait parameters: Significant differences in the right (P 0.002) and left (P 0.038) step length as well as for the right (P 0.002) and left (P 0.001) stride length. Regarding speed, only significant changes in right leg (P 0.011) Angular values: Significant changes for the right ankle (P 0.044) in support phase. Significant changes in the left knee, with increased flexion in the phase of medium support (P 0.002), terminal support (P 0.017) and initial sway (P 0.004). The hip does not present significant changes in the right or left leg during the initial contact (P 0.649–0.755), pre-swing (P 0.054–0.165) or terminal sway (P 0.738–0.896) Significant differences in the movement of the pelvis in the sagittal plane in the medium support phase for the right limb (P 0.038) and in the initial sway phase for the left limb (P 0.043). In the frontal plane, there were significant differences in the movement of the pelvis at the maximum point of movement of the left limb (P 0.027) and at the minimum point of movement of the right (P 0.002). In the transverse plane there are no significant differences in the right or left leg
Boer (2020)¹ South Africa	Experimental	26 adults. Age 32.7 ± 6 years (13 men, 13 women) IG: 13 participants CG: 13 participants	IG: Aerobic exercise in aquatic environment. Freestyle swimming training, accompanied by lively music and strictly controlled by the main test instructor using a whistle CG: No structured intervention	Mode: Freestyle swimming in a 12-m long and 1.4-m deep pool. Swim a certain length of the pool and rest while a partner completes another length in the same lane. As soon as the partner reaches the middle of the lane, the other participant is instructed to swim Frequency: 3 times/week Duration: 20 min the first 4 weeks, 26 min the last 4 weeks	Static Balance: - Balance on one leg Dynamic Balance: - Walk on a balance beam Functional fitness: - 6MWD - 8-ft up and go Muscular strength: - Sit-to-stand test -Curl‐up modified -Isometric push‐up	Static Balance: No significant differences (P > 0.05) in IG static balance: 5.9 (3.3). CG: 5.5 (4.1). Significant differences (P < 0.05) between groups in IG dynamic balance: 5.3 (1.2). CG: 3.5 (2.6) Functional fitness: No significant differences (P > 0.05) for the 6MWD IG test: 553.8 (106.9). CG: 503.1 (118.7). Significant differences between groups (P < 0.05) in the 8-ft up and go test: IG: 5.4 (1.0). CG: 6.0 (0.9) Muscle strength: Significant differences between groups for the three tests P < 0.05: Sit-to-stand test: IG: 14.3 (1.6). CG: 13.6 (1.6). Modified curl up: IG: 33.3 (30.1). CG: 16.6 (22.1). Isometric push up: IG: 79.8 (41.9). CG: 47.3 (35.1)
Perrot et al. (2021)²⁸ France	Experimental	12 participants. Age: 35 to 64, IG: 6 participants, mean age: 49.3 CG: 6 participants, mean age: 51.4	IG: Wii based exercise program using the Nintendo Wii, a video game console with integrated motion-sensitive technology and the Nintendo Wii Balance Board to record weight and center of pressure trajectory. Each training session was supervised by the master student in adapted physical activity CG: no lifestyle changes	Mode: Wii-based exercise program First period: Wii sports (Wii Tennis and Wii Bowling) Second period: Wii Fit Plus using the balance board to play Wii Soccer Headers, Wii Ski Jump, Wii Hula Hoop, and the Wii Marbles games Duration: 1 h/session for 14 weeks Frequency: 2 sessions/week	Functional mobility: - TUG - TUDS Muscular endurance: The 30-s chair stand test Physical fitness: 6-Minute Walk Test	Improvement in the IG was observed with large effect sizes for functional measures (p < 0.01, Cohen’s d = 2.23), muscular endurance (p < 0.05; Cohen’s d = 1.74), and physical fitness (p < 0.05, Cohen’s d = 1.39) The TUG and TUDS scores increased respectively by 15% and 12%, muscular endurance by 24%, and physical fitness by 5%
Post et al. (2022)³¹ United States of America	Quasi- experimental	IG: 6 men and 5 women clinically diagnosed with Down syndrome Age: 25.8 ± 6.4 years IQ: 58.3 ± 19.7 units	10-week resistance training exercise protocol	Mode: Light Repetition Maximum (RM) (12–15 RM), moderate (8–10 RM), and heavy (4–6 RM) for three sets. It included: warm-ups from large to smaller muscle groups (leg press, bench press, leg curl, shoulder press, bicep curls, and variations to make it enjoyable each day). Exercises were performed with machines, free weights, resistance bands, and body weight alone Duration: 45–60 min/session for 10 weeks	Motor Function Testing: The TGMD-2 (short sprint, gallop, shuffle, stationary basketball dribble, catch a baseball) Flexibility: sit-and-reach test Muscular Strength: 6-repetition maximum testing for the leg press, and bench press, as well as the 30-s chair sit-to-stand test Muscular endurance: 30-s of push-ups and 30-s of sit-ups	Participants significantly improved both locomotor skill (p = 0.001), object control skill (p = 0.008), and total gross motor function (p = 0.000) This intervention significantly improved sit-and-reach flexibility, 6 RM barbell bench press, 6 RM supine leg press, 30-s push-ups, 30-s sit-ups, and 30-s chair sit-to-stand metrics
Cai and Baek (2022)²⁹ China	Experimental	22 adults (18 men and 4 women) with DS between 18 to 40 years IG: 11 participants CG: 11 participants	IG: Basketball programme, strictly supervised, conducted in a 28-m long, 15-m wide, international standard basketball court of Basketball CG: Performed no structured exercises	Mode: Basketball programme - Warm up with games for 10 min - 45 min of basic basketball skill learning (shooting, passing and handling) and physical training - Relaxing exercises for 5 min Frequency: 3 times/week Duration: 60 min/session for 24 consecutive weeks	Aerobic fitness: 16-m modified shuttle-run test or PACER test Balance: - Static: standing on one leg to a maximum period of 10 s - Dynamic: number of consecutive steps (max six steps) walking on a 3.05-m balance beam that was 10.2 cm wide Muscular strength: - As many curls up as possible (maximum of 75) sliding their hands up along the upper legs to the kneecap - Standing long jump (explosive force of the lower limbs): Distance between the initial line to the heel after jumping Flexibility: The sit-and-reach test	After 24 weeks there was a statistically significant improvement in all functional health variables in the IG (all featured P < 0.05) The CG had no statistically significant difference between all functional health variables except for the standing long jump (all featured P > 0.05) The IG had better flexibility, sit and-reach, modified curl-up, aerobic capacity and static and dynamic balance than the control group (P < 0.05)

Study

Study design

Participants

Intervention

Dosage

Outcome measurement instrument

Results

Davis and Sinning (1987)³³

United States of America

Quasi- experimental

IG1: 6 men with DS. Age: 20–38.2 years. IQ ranging 32–41

IG2: 6 men with mental disabilities without DS. Age 18.5–36.2 years. IQ ranging 33–57

CG: 6 undergraduate and postgraduate students. Age: 19–24.3 years. Above average IQ

IG1 AND IG2: Strength training under the supervision of graduates and graduates in physical education who were instructed in the procedures. Individual records of weight, series and repetitions were set

CG: They exercised individually and recorded their own progress

Mode: bench press, triceps curls, and biceps curls with free weight

Intensity: 6–8 repetitions. The amount of weight for each particular set was progressively increased as the subjects were able to exceed 8 repetitions

Duration: 8 weeks

Frequency: 3 times a week

Elbow flexor strength:

Maximum voluntary contraction: supine, right arm in 90° elbow flexion, exert 2 maximum efforts against immovable resistance. In the same position, exert a force for 5 s against a series of loads ranging from 5 lb to approximately 90% of the maximum effort measured

Electromyography:

Electrodes are placed on the flexor muscle group at the elbow (biceps brachii). Integrated EMG and torque measurements of the elbow flexor muscle group were recorded simultaneously during maximal effort and step loading procedures

Only half of the subjects increased their maximum voluntary contraction as a result of the training, but there were no significant differences between groups P > 0.05

As expected, the post measurements of the group without disabilities experienced more improvement than the other two groups with disabilities, being statistically significant. p < 0.001

Carmeli et al. 2002¹⁰

Israel

Experimental

26 older adults aged 57–65 years

Mild mental retardation

IQ ranging 56–75 according to the Stanford Binet scale

IG: 16 participants (10 women, 6 men)

CG: 10 participants (6 women, 4 men)

IG: Aerobic exercise with treadmill walking

Participants walked only between 9:30 and 11:30 am indoors under controlled conditions (23 °C, 40% humidity)

CG: They were instructed not to change their daily activity level

Mode: Endless treadmill walk

Intensity: Low resistance with 0% incline

Intensity: Speed below the threshold for breathlessness but as fast as they could comfortably tolerate

Frequency: 3 times/week

Duration: 25 consecutive weeks. They initially walked for 10–15 min. The duration was gradually increased up to 45 min according to tolerance

Dynamic balance and gait speed:

- Timed up and go

Muscle strength:

- Flexion (hamstrings) and extension (Quadriceps) of the knee in the isokinetic system (Biodex dynamometer) at speeds of 60°/s and 120°/s

Data were collected for peak torque (ft/lb) (highest individual value of three peak efforts), peak torque percentage of body weight (ft/lb/kg), and average power (watts)

Timed up and go: IG: 25.9 ± 3 s. CG: 29.1 ± 3 s. Significant improvements between groups p < 0.05

Muscle strength: Significant differences are found in all three tests (maximum torque, % maximum torque of body weight and average power) of hamstrings and quadriceps in both men and women p < 0.01

Rimmer et al. (2004)¹⁶

United States of America

Experimental

52 adults with DS. Mean age 39.4 ± 6.4

IG: 30 participants

CG: 22 participants. without intervention

IG: Cardio and strength exercises

Exercise classes were supervised by a full-time registered clinical exercise physiologist and two assistants

CARDIOVASCULAR TRAINING

Mode: Recumbent stepper, stationary cycle (recumbent and upright), treadmill and elliptical

Duration: 15–20 min the first 2 weeks, 20–30 min the third and fourth weeks, 30 min from the fifth week onward for 12 weeks

Intensity: 50%–70% of VO2 max. Monitored with cardiac monitors

STRENGTH TRAINING

Mode: seated bench and leg press, seated leg curl, triceps curl, seated shoulder press, seated row, push-up

Duration: 15–20 min

Intensity: initially 70% of 1-RM for a set of 10–20 reps. When participants were able to complete 20 reps for 2 consecutive sessions with proper lifting technique, the weight was increased by 10% of their 1-RM

Strength: 1-RM protocol according to the ACSM

Leg press

Chest press

Grip Strength:

Manual dynamometry

Leg Press: IG: 320 lb (87) 145.1 kg (39.4). CG: 208 lb (97) 94.3 kg (43.9). Significant differences p < 0.0001

Chest Press: IG: 100.7 lb (44.9) 45.6 kg (20.3). CG: 59.9 lb (33.6) 27.1 kg (15.2). Significant differences p < 0.0001

Dynamometry:

IG: Right hand 22.0 (8.1); Left hand 21.6 (8.7)

CG: Right hand 19.0 (7.7); Left hand 17.8 (7.0)

Nonsignificant differences neither on the left nor on the right side p > 0.05

Tsimaras and Fotiadou (2004)³⁰

Greece

Quasi-experimental

25 adults with DS all from the Center of Professional Learning of Thessaloniki

IG: 15 participants. IQ range, 45–60. Age, 24.5 ± 3.9 years

CG: 10 participants. (IQ range, 45– 59. Age 24.7 ± 2.7 years

IG: a 12-week Cardio and strength training

Mode: walking, slow running, and free gymnastic activities that mobilize large muscle groups (10 min)

15–20 min of training program activities:

1. Two-foot ankle hop. 2. Single-foot side-to side ankle hop. 3. Tuck jump with knees up. 4. Tuck jump with heel kick. 5. Standing long jump. 6. Standing jump over barrier. 7. Single leg hops. 8. Double leg hops. 9. Standing on 1 foot. 10. Rocking boats. 11. Walking on line. 12. Walking across 30-cm-wide balance beam. 13. Walking across 20-cm-wide balance beam. 14. Walking across 10-cm-wide balance beam

Finally, 5-min recovery period

Frequency: 3 times per week,

Duration: 30–35 min/sesion

Peak torque of knee extension and flexion: Cybex II isokinetic dynamometer

Isokinetic muscle endurance of quadriceps muscles: after 25 repeated maximum efforts at an angular velocity of 180° , and it was defined by the percentage of decline from the peak torque

Dynamic balance ability: balance deck. Number of seconds the subject could remain standing on the platform of the stabilometer in durations of 30-, 45-, and 60-s intervals

Isokinetic peak torque of anterior (300, 180, 120° p < 0.001, 60°p < 0.01) and posterior (300, 180, 120° p < 0.01, 60° p < 0.01) femoral muscles significantly improved for the experiment group

The isokinetic endurance: it showed a significant improvement (p < 0.01) after participation in the training program

Dynamic balance ability: was significantly improved for the experiment group (30 s p < 0.01, 45 s and 60 s p < 0.001,

No significant differences were found in any of the measurements for the control group

For the initial and final measurements, no statistically significant differences were found between the 2 groups

Aguiar et al. (2008)²⁷

Brazil

Quasi-experimental

IG: 21 men Age: 23.3 ± 2.1

Monitored aerobic exercise of adapted judo training for 16 weeks

Mode: Adapted Judo

Intensity: Lactate threshold

Frequency: 3 times/week

Duration: 50 min/session

Gross motor skills:

GMFM-88

The judo training program significantly (P < 0.05) improved the GMFM-88 index of young adults with DS

Shields et al. (2008)⁸

Australia

Experimental

20 adults. Age: 26.8 ± 7.8 years

13 men, 7 women

IG: 9 participants

CG: 11 participants

8 of the 20 participants worked at least 1 day/week in manual-type jobs (packing confectionery boxes, sorting and cutting clothes, and assembling car parts)

IG: Group progressive resistance training in a supervised community gym. The trainer kept a record for each participant of the number of repetitions and sets and the weight lifted/exercised in each session. Participants completed the program in a group, supervised by 2 accredited fitness trainers. Each trainer supervised the training of a subgroup of 2–3 participants

CG: Continued with usual activities (work, free time, and leisure)

Mode: Progressive resistance training with machines:

- Shoulder press

- Seated chest press

- Seated rowing

- Seated leg press

- Knee extension

- Seated calf raise

Intensity: Increased when 2 sets of 12 reps per exercise could be completed

Volume: 2–3 sets of 10–12 reps per exercise to failure

Frequency: 2 times a week

Duration: 10 weeks

Density: 2-min rest between sets

Muscle performance:

- 1 RM: Chest press and leg press

- Muscular resistance: repetitions of chest and leg press with 50% of 1RM

Physical function:

- Timed up and down stairs test

- Grocery shelving task: Get up from a chair and take 2 bags of groceries to a bench located 2 m away. Each bag contains 10 items (410 g each, total weight of each bag 4.1 kg). Then they have to take the items out of the bag and stack them on a shelf at shoulder height

1 RM Chest Press: IG: 44.9 ± 15.2 kg. CG: 31.6 ± 13.3 kg

1 RM Leg Press: IG: 96.2 ± 31.6 kg. CG: 82.2 ± 19.7 kg

Rep Chest Press: IG: 25.9 ± 8.3. CG 17.5 ± 9.5

Rep Leg Press: IG: 46.8 ± 37.1. CG: 49.4 ± 27.6

Timed up and down stairs: IG: 14.4 ± 3.4 s. CG: 18.7 ± 6.5 s

Grocery shelving task: IG: 67.5 ± 33.4 s. CG: pre 122.8 ± 84.0 s; post 110.7 ± 66.4 s

Significant differences between groups in 1-RM chest press (P 0.08), chest press repetitions (P 0.002), and leg press repetitions (P 0.039)

No significant differences between groups in the leg press 1RM test (P 0.90), timed up and go (P 0.12) or grocery shelving task test (P 0.11)

Cowley et al. 2011⁹

United States of America

Quasi- experimental

30 adults with mild intellectual disabilities. Age: 28 ± 8 years

IG: 9 men and 10 women

CG: 11 participants. 8 men and 3 women

IG: progressive resistance training

Each participant worked one on one with a professional who supervised all the training sessions

CG: Maintained normal daily activities

Mode: Leg extension, leg curl, leg press, shoulder press, chest press, bicep curl, and tricep curl exercises performed on exercise machines

Intensity: 3 sets of 8–10 reps per exercise. The weight lifted by the subject was recorded during the training period and progressively increased to constantly overload the muscle

Frequency: 2 days per week

Duration: 10 weeks

Isometric and isokinetic strength of knee extensors and flexors: Biodex System 3 dynamometer

- Maximum isometric peak torque: 3 series of 3 maximum contractions with knee extensors and flexors at a joint angle of 45°, 60°, and 75° with 3 min interval between series

- Maximum isokinetic peak torque: 3 series of 5 maximum contractions with knee extensors and flexors at 60°/s with 3 min interval between series

Functional tasks of daily life:

- Time to get up from a chair at different heights (30, 38, or 43 cm) as quickly as possible to an upright position with trunk and legs straight, keeping arms crossed over the chest

- Gait speed: Walk 7.62 m

- Go up and down 10 steps as fast as possible without using the support handrail and alternating feet and then go down

Isometric flexor strength:

Significant differences between groups P < 0.05 in the three degrees of movement (45°, 60°, and 75°)

Isometric strength extensors:

Significant differences in the IG in the three degrees of movement P < 0.05

Flexors and extensors isokinetic strength Significant differences in the IG P < 0.05

Getting up from a chair at different heights: No significant differences P > 0.05 in any of the chair heights (30 cm, 38 cm, 43 cm) or in the 5 repetitions

10-step ascent and descent: Significant differences in the IG P < 0.05 in both tests. IG Ascent: .83 SD 1.19. CG: 5.10 SD 1.19. GI descent: 4.38 SD 1.19. CG: 6.23 SD 2.80

Gait speed: IG: 1.72 SD 0.20. CG: 1.71 SD 0.24. No significant differences P > 0.05

Mendonca et al. (2011)¹⁵

Portugal

Quasi- experimental

IG1: 13 participants (10 men, 3 women) with DS. Age: 36.5 ± 5.5 years

IG2: 12 participants (9 men, 3 women) without disabilities. Age: 38.7 ± 8.3 years

Combined resistance and strength exercise training

The exercise sessions were supervised by an exercise physiologist and an assistant

ENDURANCE TRAINING

Mode: Walk or run on a treadmill

Intensity: target heart rate compatible with 65% (first three weeks) at 85% of VO2peak. Monitored with fc/participant clock

Duration: 30 min. 12 weeks

Frequency: 3 days/week

STRENGTH TRAINING

Mode: repeating a set of 9 exercises twice with < 30 s of rest between them. Train with leg press, chest and shoulder press, vertical pull, lower back, leg extension, bicep curl, and tricep curl. In addition, 1 set of 15 repetitions of abdominal push-ups in each rotation

Intensity: 10% increase in 12-RM load when participants were able to complete 14 reps for 2 consecutive sessions with proper technique

Frequency: 2 days/week

Muscle strength: 12-RM protocol on variable resistance machines

- Leg press

- Chest press

- Vertical traction

- Lower back

- Leg extension

Each participant was asked to perform 15 reps with relatively light resistance followed by 30 s of recovery. Resistance was then increased, and each participant performed a maximum of 5 sets of 12 repetitions until the 12-RM was reached. The recovery period between sets was exactly 2 min, and increments of 2.5–5 kg were used as each participant approached fatigue. The 12-RM was defined as the maximum load lifted through a full range of motion for a total of 12 repetitions. For most participants, the 12-RM was determined in 3–4 attempts

Leg Press: IG1: 110.2 ± 52.6. IG2: 171.3 ± 56.5

Chest Press: IG1: 35.3 ± 12.2. IG2: 51.3 ± 21.0

Vertical Traction: IG1: 39.2 ± 14.1. IG2: 59.4 ± 15.3

Lower Back: IG1: 35.6 ± 7.4. IG2: 51.9 ± 19.3

Leg Extension: IG1: 30.1 ± 10.3. IG2: 52.7 ± 17.6

Participants with Down syndrome showed lower muscle strength than participants without disabilities in all dynamic exercises, both before and after training

Training was highly efficient in obtaining generalized improvements for 12-RM in both groups (P < 0.05). The magnitude of these improvements was similar between participants with and without Down syndrome

Boer and Moss, (2016)⁵

South Africa

Experimental

42 adults. Age 33.8 ± 8.6

(25 men, 17 women)

IG1: 13 participants

IG2: 13 participants

CG: 16 participants

IG1: Continuous aerobic training (CAT) on a bicycle or treadmill

IG2: Interval training (IT) with 10–30-s sprints on a bike or treadmill

The two IGs performed the intervention under the supervision of a licensed sport scientist and exercise physiologist in a 2:6 (professional:participants) ratio

CG: No intervention

Duration: 12 weeks. 30-min sessions the first six weeks (5-min warm-up, 20-min central act, 5-min cool down), the last six weeks’ sessions were increased by 5 min for the central activity

Intensity: Warm up and cool down at 4 km/h

Frequency: 3 times/week

IG1: CAT

- Mode: Continuous aerobic training by bicycle (50%) or treadmill (50%)

- Central act intensity: first six weeks 70%–80% VO2peak, last 6 weeks 85% VO2peak

IG2: IT

- Mode: Interval aerobic training on a bicycle (50%) or treadmill (50%)

- Intensity: 10–30-s max sprints with 90-s low cadence, low intensity gait, or bike

Grip strength:

- Manual dynamometry in the dominant hand

Lower Body Strength:

- Sit-to-stand test

Agility and dynamic balance:

- 8-ft up and go

Aerobic capacity and functional ability:

- 6MWD

Grip strength:

CAT: 26.1 kg (7.9). IT: 29.9 kg (8.9). CG: 25.5 kg (9.1). No significant differences between groups P = 0.57

Lower Body Strength:

CAT: 15.2 (1.8). IT: 15.5 (1.8). CG: 13.3 (2.3). Significant improvements between groups P = 0.01 and only in the CAT group compared to the control group (P < 0.05)

Agility and balance:

CAT: 4.8 s (0.9). IT: 4.9 s (1.1). CG: 6.2 s (1.3). Significant improvements between groups P = 0.03 and only in the CAT group compared to the control group (P < 0.05)

Aerobic capacity and functional ability:

CAT: 563.2 m (74.9). IT: 562.6 m (81.7). CG: 495.9 m (85.2). Significant improvements between groups P = 0.01 and only in the CAT group compared to the control group (P < 0.05)

Silva et al. (2017)³²

Portugal

Experimental

27 adults aged 18–60 years

IG: 14 participants

CG: 13 participants

IG: Wii-based exercise program that included training games for aerobic endurance, balance, and isometric strength

CG: They completed their usual daily activities (usual treatment) at their occupational center, such as rehabilitation, life skills training, and art-related activities

Mode: Aerobic exercise through a Wii-based exercise program. Individual sessions or with another participant (half of the sessions in each format)

Frequency: 3 sessions per week

Duration: 2 months

Physical aptitude: Eurofit test battery:

- Limb movement speed (Plate Tapping Test)

- Static arm strength (Handgrip Test)

- Running speed and agility (Shuttle Run)

- Balance (Flamingo Balance)

- Flexibility (Sit and Reach)

- Explosive power of the legs (Standing Broad)

- Trunk Strength (30-s Sit-ups)

- Muscular resistance (Bent Arm Hang)

Functional mobility:

- Timed Up and Go

- Response speed subtest of the Bruininks–Oseretsky Motor Competence Test First Edition

Motor skills:

- Beanbag Overhead

Significant improvements in the GI in the Handgrip test (IG: 25.42 (5.53). CG: 23.92 (6.45) P 0,025), in the sit and reach (IG: 36.92 (7.22). CG: 29.46 (10.53) P 0,014), in the standing broad (IG: 99.33 (29.49). CG: 90.69 (35.20) P < 0,001) and in the Bruininks–Oseretsky First Edition test (IG: 4.67 (2.81). CG: 4.77 (2.17) P 0.028)

Significant differences between groups were identified in the plate tapping test (P 0.045), shuttle run (P 0.014), sit and reach (P 0.027), standing broad (P 0.003), 30-s sit-ups (P 0.040) and timed up and go (P 0.049)

No significant differences in the handgrip test (P 0.837), flamingo balance (P 0.477), bent arm hang (P 0.086), Bruininks–Oseretsky First Edition (P 0.265), neither in the beanbag overhead nor in the hand right P 0.150 nor in the left P 0.083

Boer and de Beer (2019)²

South Africa

Quasi- experimental

23 adults. Age 31.4 ± 7.4 years

IG: 13 participants (8 men, 5 women)

CG: 10 participants (5 men, 5 women)

IG: Aerobic exercise in aquatic environment. Aquatic training. Sessions controlled and monitored by test instructors and senior Human Movement Sciences students (approximately one test instructor per two participants)

CG: No intervention additional to ADLs

Mode: Aquatic training with arm circle exercises, lateral twists, walk in place, run in place, water scoops, lateral leg raises, back flutter kick, stomach flutter kick, jumping jacks, knee twists, side shift, squat jumps, lunge jumps, and longer jog, 1.4-m-deep pool

Duration: 6 weeks, 35 min the first 3 weeks, 45 min the last 3 weeks. Consider a 3-min warm up and 2-min cool down

Frequency: 3 times/week

Static Balance:

- Balance on one leg

Dynamic Balance:

- Walk on a balance beam

Functional fitness:

- 6MWD

- 8-ft up and go

Muscular strength:

- Sit-to-stand test

-Curl‐up modified

-Isometric push-up

Static Balance:

No significant differences P > 0.05 in the static balance IG: 6.6 (3.5). CG: 5.1 (3.6), nor dynamic IG: 5.6 (0.8). CG: 4.6 (2.1)

Functional fitness:

Significant differences between groups P < 0.05 for the 6MWD test: IG: 602.1(98.7). CG: 519. 9 (111.9). No significant differences P > 0.05 in the 8-ft up and go test: IG: .3 (0.9). CG: .5 (0.9)

Muscle strength:

Significant differences between groups P < 0.05 for sit-to-stand test GI: 14.5 (2.2). CG: 13.0 (1.8) and modified curl up GI: 37.9 (30.1). CG: 20.0 (28.3). Nonsignificant differences P > 0.05 for isometric push-up IG: 82.2 (50.9). CG: 36.5 (32.5)

Skiba et al. (2019)¹³

Polonia

Experimental

22 adults aged 25– 40 years, with moderate intellectual disability (IQ: 36–51). 11 men, 11 women

IG: 11 participants. CG: 11 participants

IG: Aerobic exercise with Nordic walking training program. The exercises were performed by a physiotherapist, who was a qualified Nordic walking instructor

CG: Did not undergo any training

Mode: Brisk Nordic walking

Intensity: Progressed over the course of the training sessions

Frequency: 3 times a week

Duration: 45 min

Spatiotemporal parameters (step and stride length and speed) and maximum values of angles in the ankle, knee, hip, and shoulder joints in different phases of gait:

Using the Vicon 250 Optoelectronic System for Three-Dimensional Motion Analysis

Gait parameters: Significant differences in the right (P 0.002) and left (P 0.038) step length as well as for the right (P 0.002) and left (P 0.001) stride length. Regarding speed, only significant changes in right leg (P 0.011)

Angular values: Significant changes for the right ankle (P 0.044) in support phase. Significant changes in the left knee, with increased flexion in the phase of medium support (P 0.002), terminal support (P 0.017) and initial sway (P 0.004). The hip does not present significant changes in the right or left leg during the initial contact (P 0.649–0.755), pre-swing (P 0.054–0.165) or terminal sway (P 0.738–0.896)

Significant differences in the movement of the pelvis in the sagittal plane in the medium support phase for the right limb (P 0.038) and in the initial sway phase for the left limb (P 0.043). In the frontal plane, there were significant differences in the movement of the pelvis at the maximum point of movement of the left limb (P 0.027) and at the minimum point of movement of the right (P 0.002). In the transverse plane there are no significant differences in the right or left leg

Boer (2020)¹

South Africa

Experimental

26 adults. Age 32.7 ± 6 years (13 men, 13 women)

IG: 13 participants

CG: 13 participants

IG: Aerobic exercise in aquatic environment. Freestyle swimming training, accompanied by lively music and strictly controlled by the main test instructor using a whistle

CG: No structured intervention

Mode: Freestyle swimming in a 12-m long and 1.4-m deep pool. Swim a certain length of the pool and rest while a partner completes another length in the same lane. As soon as the partner reaches the middle of the lane, the other participant is instructed to swim

Frequency: 3 times/week

Duration: 20 min the first 4 weeks, 26 min the last 4 weeks

Static Balance:

- Balance on one leg

Dynamic Balance:

- Walk on a balance beam

Functional fitness:

- 6MWD

- 8-ft up and go

Muscular strength:

- Sit-to-stand test

-Curl‐up modified

-Isometric push‐up

Static Balance:

No significant differences (P > 0.05) in IG static balance: 5.9 (3.3). CG: 5.5 (4.1). Significant differences (P < 0.05) between groups in IG dynamic balance: 5.3 (1.2). CG: 3.5 (2.6)

Functional fitness:

No significant differences (P > 0.05) for the 6MWD IG test: 553.8 (106.9). CG: 503.1 (118.7). Significant differences between groups (P < 0.05) in the 8-ft up and go test: IG: 5.4 (1.0). CG: 6.0 (0.9)

Muscle strength:

Significant differences between groups for the three tests P < 0.05: Sit-to-stand test: IG: 14.3 (1.6). CG: 13.6 (1.6). Modified curl up: IG: 33.3 (30.1). CG: 16.6 (22.1). Isometric push up: IG: 79.8 (41.9). CG: 47.3 (35.1)

Perrot et al. (2021)²⁸

France

Experimental

12 participants. Age: 35 to 64,

IG: 6 participants, mean age: 49.3

CG: 6 participants, mean age: 51.4

IG: Wii based exercise program using the Nintendo Wii, a video game console with integrated motion-sensitive technology and the Nintendo Wii Balance Board to record weight and center of pressure trajectory. Each training session was supervised by the master student in adapted physical activity

CG: no lifestyle changes

Mode: Wii-based exercise program

First period: Wii sports (Wii Tennis and Wii Bowling)

Second period: Wii Fit Plus using the balance board to play Wii Soccer Headers, Wii Ski Jump, Wii Hula Hoop, and the Wii Marbles games

Duration: 1 h/session for 14 weeks

Frequency: 2 sessions/week

Functional mobility:

- TUG

- TUDS

Muscular endurance: The 30-s chair stand test

Physical fitness: 6-Minute Walk Test

Improvement in the IG was observed with large effect sizes for functional measures (p < 0.01, Cohen’s d = 2.23), muscular endurance (p < 0.05; Cohen’s d = 1.74), and physical fitness (p < 0.05, Cohen’s d = 1.39)

The TUG and TUDS scores increased respectively by 15% and 12%, muscular endurance by 24%, and physical fitness by 5%

Post et al. (2022)³¹

United States of America

Quasi- experimental

IG: 6 men and 5 women clinically diagnosed with Down syndrome Age: 25.8 ± 6.4 years

IQ: 58.3 ± 19.7 units

10-week resistance training exercise protocol

Mode: Light Repetition Maximum (RM) (12–15 RM), moderate (8–10 RM), and heavy (4–6 RM) for three sets. It included: warm-ups from large to smaller muscle groups (leg press, bench press, leg curl, shoulder press, bicep curls, and variations to make it enjoyable each day). Exercises were performed with machines, free weights, resistance bands, and body weight alone

Duration: 45–60 min/session for 10 weeks

Motor Function Testing: The TGMD-2 (short sprint, gallop, shuffle, stationary basketball dribble, catch a baseball)

Flexibility: sit-and-reach test

Muscular Strength: 6-repetition maximum testing for the leg press, and bench press, as well as the 30-s chair sit-to-stand test

Muscular endurance: 30-s of push-ups and 30-s of sit-ups

Participants significantly improved both locomotor skill (p = 0.001), object control skill (p = 0.008), and total gross motor function (p = 0.000)

This intervention significantly improved sit-and-reach flexibility, 6 RM barbell bench press, 6 RM supine leg press, 30-s push-ups, 30-s sit-ups, and 30-s chair sit-to-stand metrics

Cai and Baek (2022)²⁹

China

Experimental

22 adults (18 men and 4 women) with DS between 18 to 40 years

IG: 11 participants CG: 11 participants

IG: Basketball programme, strictly supervised, conducted in a 28-m long, 15-m wide, international standard basketball court of Basketball

CG: Performed no structured exercises

Mode: Basketball programme

- Warm up with games for 10 min

- 45 min of basic basketball skill learning (shooting, passing and handling) and physical training

- Relaxing exercises for 5 min

Frequency: 3 times/week

Duration: 60 min/session for 24 consecutive weeks

Aerobic fitness: 16-m modified shuttle-run test or PACER test

Balance:

- Static: standing on one leg to a maximum period of 10 s

- Dynamic: number of consecutive steps (max six steps) walking on a 3.05-m balance beam that was 10.2 cm wide

Muscular strength:

- As many curls up as possible (maximum of 75) sliding their hands up along the upper legs to the kneecap

- Standing long jump (explosive force of the lower limbs): Distance between the initial line to the heel after jumping

Flexibility: The sit-and-reach test

After 24 weeks there was a statistically significant improvement in all functional health variables in the IG (all featured P < 0.05)

The CG had no statistically significant difference between all functional health variables except for the standing long jump (all featured P > 0.05)

The IG had better flexibility, sit and-reach, modified curl-up, aerobic capacity and static and dynamic balance than the control group (P < 0.05)

IG Intervention group, CG Control group, DS Down Syndrome, IQ Intelligence quotient, EMG Electromiography, ACSM American College of Sports Medicine, GMFM-88 The Gross Motor Function Measure 88, 6MWD 6-min walking distance test, ADL’S Activities of daily living. TUG: The Timed Up and Go test, TUDS Timed Up and Down Stairs test, TGMD-2 Test of Gross Motor Development version 2.