Table 3.
Characteristics of the included studies, their participants and muscle remodelling outcome.
| First Author, Year of Publication | Country | Participant Group (n); | Age ± SD | Study Design | Experimental Group Intervention | Experimental Duration and Frequency, | Attrition | Outcome Measures | Δ Muscle Remodelling Post-Training (within Group) | Δ Muscle Remodelling Post-Training (between Groups) |
|---|---|---|---|---|---|---|---|---|---|---|
| Sex (n, %) | or ± SEM(*) | Dosage (h) | (Reasons) | |||||||
| Damas et al., 2018 [24] | Brazil | Exercise (9); Male (9, 100%) | 26 ± 2 | Pre–post study | RET: it involved two exercises for lower body. | 10 weeks (2x/week) Dosage = N/A |
1 participant (male) removed | N/A | N/A | N/A |
| Deshmukh et al., 2021 [25] | Denmark | Exercise (5); Male (5, 100%) | 24 ± 1 * | Sub-cohort of pre–post study | AET: participants performed indoor cycling exercise (intensity ranged from 75–90% of maximal heart rate): 3 out of 4 sessions performed at home, 1 out of 4 at the laboratory. | 12 weeks (4x/weeks) Dosage = 48 |
None | NA | NA | NA |
| Fragala et al., 2014 [43] | USA | Exercise (12); Male (7, 58.3%), Female (5, 41.7%) | 70.5 ± 6.9 | Pilot RCT | Supervised RET: 60–90 min (≈70–85% of RM). |
6 weeks (2x/week) Dosage = 12–18 |
None |
Muscle strength/
capacity |
||
| Leg extension strength (kg) | Exercise: ↑ 29.0% (p < 0.001) Control: NS |
NS | ||||||||
| Control (11); Male (6, 54.5%), Female (5, 45.5%) | 69.6 ± 5.5 | Maintenance of normal physical activities. | Muscle quality (relative strength) | Exercise: ↑ 28.0% (p < 0.001) Control: NS |
NS | |||||
| Body composition | ||||||||||
| LBM (kg) | Exercise:↑ 0.2% (NS) | NS | ||||||||
| Control: NS | ||||||||||
| Muscle architecture | ||||||||||
| Muscle cross-sectional area (CSA) (cm2) | Exercise:↑ 8.3% (NS) Control: NS |
NS | ||||||||
| Hjorth et al., 2015 [26] | Norway | Exercise (26); Male (26, 100%) | 51.2 ± 6.6 | Pre–post study | Supervised CT: 2 intervals bicycle sessions and 2 whole body strength-training sessions per week. Each session lasted 1 h. |
12 weeks (4x/week) Dosage = 48 |
None |
Muscle strength/
capacity |
N/A | |
| Leg extension strength (kg) | ↑ 9.6% (p < 0.001) | |||||||||
| Body composition | ||||||||||
| Fat mass (L) | ↓ 8.2% (p < 0.001) | |||||||||
| Muscle architecture | ||||||||||
| Thigh muscle area (cm2) | ↑ 7.5% (p < 0.001) | |||||||||
| Ventilatory changes | ||||||||||
| VO2max (mL/kg*min) | ↑ 11.2% (p < 0.001) | |||||||||
| Kanzleiter et al., 2014 [27] | Norway/Germany | Exercise (26); Male (26, 100%); Normal glucose group (13); Pre-diabetes group (13) | 51.2 ± 6.6 | Pre–post study | Supervised CT: 2 intervals bicycle sessions and 2 whole body strength-training sessions per week. Each session lasted 1 h. |
12 weeks (4x/week) Dosage = 48 |
None | N/A | N/A | N/A |
| Karlsen et al., 2020 [28] | Denmark | Pre–post study | Supervised heavy-load RET: sessions involved 3 exercises for lower body and 2 optional for upper body | 13 weeks (3x/week) Dosage = N/A |
2 Five old and two young participants did not complete the intervention. |
Muscle strength/
capacity |
N/A | |||
| Isometric knee extensor peak torque (Nm) | Young: ↑ 14.4 % (p < 0.01) |
|||||||||
| Older: ↑ 14.3% (p < 0.001) |
||||||||||
| Isokinetic knee extensor peak torque (Nm) | Young: ↑ 11.9% (p < 0.05) |
|||||||||
| Older: ↑ 9% (p < 0.05) |
||||||||||
| Body composition | ||||||||||
| Thin lean mass (kg) | Young: ↑ 6.7% (p < 0.001) |
|||||||||
| Young (7); Male (7, 100%) | 25 ± 3 | Older: ↑ 6% (p < 0.001) |
||||||||
| Muscle architecture | ||||||||||
| Older (19); Male (19, 100%) | 67 ± 4 | CSA VL (μm2) | Young: ↑ 11.9% (p < 0.001) |
|||||||
| Older: ↑ 14.5% (p < 0.001) |
||||||||||
| CSA QF (μm2) | Young: ↑ 8.9% (p < 0.01) |
|||||||||
| Older: ↑ 10.8% (p < 0.001) | ||||||||||
| CSA type I fibres (μm2) | Young: ↓0.2% (NS) Older: ↑ 5.7% (NS) |
|||||||||
| CSA type II fibres (μm2) | Young: ↑ 10.2% (NS) | |||||||||
| Older: ↑ 25.8% | ||||||||||
| (p < 0.001) | ||||||||||
| Type I fibres (%) | Young: ↓ 2.3% (NS) | |||||||||
| Older: ↑ 1.9% (NS) | ||||||||||
| Kern et al., 2014 [29] | Italy/Austria | 73.1 ± 6.9 | Pre–post study | ES training at home: performed with a two-channel custom-built battery-powered stimulator3 × 10 min each session. | 9 weeks (2x/week for the first 3 weeks and 3x/week for the following 6 weeks) Dosage = 12 |
None |
Muscle strength/
capacity |
N/A | ||
| Torque (Nm/kg) | ↑ 6.0 ± 4.9 (p < 0.05) | |||||||||
| Muscle architecture | ||||||||||
| All fibres size (μm) | NS | |||||||||
| Exercise (16); Male (8, 50%), Female (8, 50%) | Type I fibres size (μm) | ↓ 3.6% (p < 0.0001) | ||||||||
| Type I fibres percentage (%) | ↓ 7.2% (N.S) | |||||||||
| Type IIa fibres size (μm) | ↑ 2.2% (p < 0.0001) | |||||||||
| Type IIa fibres percentage (%) | ↑ 8.9% (N.S) | |||||||||
| Kim et al., 2015 [44] | Korea | Exercise (22); Female (22, 100%) | 74.5 ± 0.6 * | RCT | RET: it involved 2 supervised and 3 home-based sessions. Progressive intensity of the intervention. | 12 weeks (5x/week) Dosage = 60 |
3 Ten participants did not complete the intervention. |
Muscle strength/
capacity |
||
| Grip strength (kg) | Exercise:↑ 27.0% (p < 0.001) | p < 0.001 | ||||||||
| Knee extensor strength 60°/s (N) | Exercise:↑ 42.1% (p < 0.001) | p = 0.019 | ||||||||
| Knee flexor strength (N) | Exercise:↓ 1.5% (NS) | p = 0.002 | ||||||||
| Control (8); Female (8, 100%) | 76.05 ± 2.0 * | Maintenance of normal physical activities and performance of one hour stretching once a week | Knee extensor strength 180°/s (N) | Exercise:↑ 33.7% (NS) | NS | |||||
| Knee flexor strength (N) | Exercise:↓ 19.4% (p < 0.001) | p = 0.028 | ||||||||
| Body composition | ||||||||||
| Waist–hip ratio (WHR) | Exercise:↓ 1.2% (NS) | N/A | ||||||||
| Arm circumference (cm) | Exercise:↓ 5.1% (NS) | N/A | ||||||||
| Thigh circumference (cm) | Exercise:↓ 1.3% (NS) | N/A | ||||||||
| Makhnovskii et al., 2020 [30] | Russia | Exercise (7); Male (7, 100%) | 22.5 ± 1.5 * | Pre–post study | AET: participants alternated continuous (intensity at 70% LT4) and intermittent exercise ((3 min, 50% LT4 + 2 min, 85% LT4) x12)) on different days. | 5 weeks (7x/week) Dosage = 35 |
None | N/A | N/A | N/A |
| Nishida et al., 2010 [31] | Japan | Exercise (6); Male (6, 100%) | 19–32 | Pre–post study | Supervised AET: participants performed the session for 60 min using an upright cycle ergometer. Training intensity at the LT level. | 12 weeks (5x/week) Dosage = 60 |
None | Body composition | N/A | |
| Fat percentage (%) | ↓ 2.2% (NS) | |||||||||
| Ventilatory changes | ||||||||||
| VO2max (mL/kg * min) | ↑ 8.7% (NS) | |||||||||
| VO2 at LT (mL/kg * min) | ↑ 62.5% (p < 0.05) | |||||||||
| VO2max at LT (%) | ↑ 48.9% (p < 0.05) | |||||||||
| Norheim et al., 2011 [32] | Norway | Exercise (13); Male (13, 100%) | 26.8 (19–35) | Sub-cohort of pre–post study | RET: it involved 1–3 sets of leg press, leg extension, leg curl, seated chest press, seated rowing, latissimus dorsi pull-down, biceps curl, and shoulder press. |
11 weeks (3x/week) Dosage = N/A |
None | N/A | N/A | N/A |
| Norheim et al., 2014 [33] | Norway | Exercise (26); Male (26, 100%), Normal glucose group (13), Pre-diabetes group (13) | 51.2 ± 6.6 | Pre–post study | Supervised CT: it involved 2 interval bicycle sessions and 2 whole body strength-training sessions per week. Each session lasted 1 h. | 12 weeks (4x/week) Dosage = 48 |
None | N/A | N/A | N/A |
| Radom-Aizak et al., 2005 [35] | Israel | Exercise (6); Male (6, 100%) | 68.0 ± 2.7 * | Pre–post study | AET: participants performed 45 min sessions (from the 3rd–12th week) on a cycle ergometer at 80% of the predetermined HRmax. | 12 weeks (3x/week) Dosage = 27 |
None | Ventilatory changes | N/A | |
| VO2max (L/min) | ↑ 17.8% (p = 0.009) | |||||||||
| Anaerobic threshold (%) | ↑ 21% (p = 0.008) | |||||||||
| Raue et al., 2012 [36] | USA | Young (16); Male (8, 50%), Female (8, 50%) | 24 ± 4 | Pre–post study | RET: it involved 3 sets of 10 bilateral knee extensions (70–75% of 1 RM). | 12 weeks (3x/week) Dosage = N/A |
None |
Muscle strength/
capacity |
N/A | |
| Leg extension strength (kg) |
↑ 5.7–↑ 41.3 kg | |||||||||
| Older (12); Male (6, 50%), Female (6, 50%) | 84 ± 3 | |||||||||
| Muscle architecture | ||||||||||
| Thigh muscle CSA (cm2) | ↓ 1.2–↑ 10.4 cm2 | |||||||||
| Riedl et al., 2010 [37] | Japan | Exercise (7); Male (7, 100%) | 64 ± 2.6 | Pre–post study | Supervised AET: participants performed sessions of 60 min on a cycle ergometer. Training intensity at the LT level | 6 weeks (5x/week) Dosage = 30 |
None | Body composition | N/A | |
| Fat percentage (%) | ↓ 9.9% (p < 0.05) | |||||||||
| Ventilatory changes | ||||||||||
| VO2 at LT (%) | ↑ 8.3% (p < 0.05) | |||||||||
| VO2 max (mL/FFM kg/min) | ↑ 7.3% (p < 0.05) | |||||||||
| Robinson et al., 2017 [38] | USA | Young HIIT exercise (10); Male, Female | Pre–post study | HIIT: participants performed 3 sessions per week of cycling (4 × 4 min at >90% of VO2max separated by 3 min of pedalling at no load) and 2 sessions per week of treadmill walking (45 min at 70% of VO2max). |
HIIT: 12 weeks (5x/week) Dosage = 34.8 |
4 Five young and three older participants did not complete the intervention. There was no information on number of males and females completing the study | Young HIIT | Absolute VO2max (mL/min) in young: ↑ following HIIT (p < 0.0001) > ↑ following RET (p < 0.048) and CT (p = 0.0001) | ||
| 25.4 ± 4.3 | ||||||||||
| Ventilatory changes | ||||||||||
| VO2max (mL/kg BW/min) | ↑ (p < 0.001) | |||||||||
| Older HIIT exercise (8); Male, Female | Body composition | |||||||||
| 70.7 ± 4.6 | FFM (kg) | ↑ (p < 0.05) | ||||||||
|
Muscle strength/
capacity |
Absolute VO2max (mL/min) in older: ↑ following HIIT (p < 0.0091) and CT (p = 0.0096) >↑ following RET (ns) | |||||||||
| Young RET (10); Male, Female | 23.7 ± 3.5 | Maximal leg strength (1 RM) leg press (AU/kg Leg FFM) | ↑ (NS) | |||||||
| RET: participants performed 2 sessions of lower and upper body exercises (4 sets of 8–12 repetitions), 2 days each per week. |
RET: 12 weeks (5x/week) Dosage = N/A |
|||||||||
| Older RET (8); Female | 70.3 ± 3.9 | |||||||||
| Older HIIT | ||||||||||
| Ventilatory changes | Relative VO2max (mL/min) in young: ↑ ~28% following HIIT (p < 0.0001) > ↑ ~17% following CT (p < 0.0001) > RET (ns) | |||||||||
| Young Combined exercise (8); Male, Female | 26.3 ± 2.7 | VO2max (mL/kg BW/min) | ↑ (p < 0.01) | |||||||
| CT after a 3 months SED: Following SED, participants underwent metabolic studies and performed CT of 5 days per week cycling (30 min at 70% VO2max) and 4 days per week weightlifting with fewer repetitions than RET. | Combined:12 weeks (9x/week) Dosage > 30 |
Body composition | ||||||||
| FFM (kg) | ↑ (p < 0.05) | |||||||||
|
Muscle strength/
capacity |
||||||||||
| Older Combined exercise (7); Male, Female | 68.6 ± 3.4 | |||||||||
| Maximal leg strength (1 RM) leg press) (AU/kg Leg FFM |
↑ (NS) | Relative VO2max (mL/min) in older: ↑ ~21% following CT (p < 0.0001) > ↑ ~17% following HIIT (p < 0.0001) > RET (ns) | ||||||||
| Young RET | ||||||||||
| Ventilatory changes | ||||||||||
| VO2max (mL/kg | ↑ (NS) | |||||||||
| BW/min) | ||||||||||
| Body composition | Leg strength: ↑ Following RET and CT > HIIT (NS) |
|||||||||
| FFM (kg) | ↑ 4% (p < 0.0001) | |||||||||
| Muscle strength/ | ||||||||||
| Maximal leg strength | ↑ (p < 0.05)↑ | |||||||||
| (1 RM) leg press | ||||||||||
| (AU/kg Leg FFM) | ||||||||||
| Older RET | ||||||||||
| Ventilatory changes | ||||||||||
| VO2max (mL/kg BW/min) |
↑ (NS) | |||||||||
| Body composition | ||||||||||
| FFM (kg) | ↑ (p < 0.01) | |||||||||
|
Muscle strength/
capacity |
||||||||||
| Maximal leg strength (1 RM) leg press (AU/kg Leg FFM) | ↑ (p < 0.05) | |||||||||
| Young CT | ||||||||||
| Ventilatory changes | ||||||||||
| VO2max (mL/kg BW/min) | ↑ (p < 0.001) | |||||||||
| Body composition | ||||||||||
| FFM (kg) | ↑ (p < 0.05) | |||||||||
|
Muscle strength/
capacity |
||||||||||
| Maximal leg strength (1 RM) leg press (AU/kg Leg FFM) | ↑ (p < 0.05) | |||||||||
| Older CT | ||||||||||
| Ventilatory changes | ||||||||||
| VO2max (mL/kg BW/min) | ↑ (p < 0.01) | |||||||||
| Body composition | ||||||||||
| FFM (kg) | ↑ (p < 0.05) | |||||||||
|
Muscle strength/
capacity |
||||||||||
| Maximal leg strength (1 RM) leg press (AU/kg Leg FFM) | ↑ (p < 0.05) | |||||||||
| Timmons et al., 2010 [39] | Sweden, Denmark, UK, USA | Exercise (24); Male (24, 100%) | 23 | Pre–post study | Supervised AET: participants performed 45 min cycling sessions. Training intensity customized to 70% of the pretraining VO2max. |
6 weeks (4x/week) Dosage = 18 |
None | Ventilatory changes | N/A | |
| VO2 max (L/min) | ↑ 14% (N/A) | |||||||||
| Submax RER (ratio) | ↓ 10% (N/A) | |||||||||
| Valdivierso et al., 2017 [40] | Switzerland | Exercise (61); Male (61, 100%), A/A alleles (12), A/T alleles (38), T/T alleles (11) | 29.5 ± 9.3 | Pre–post study | AET: participants performed 30 min sessions on a cycle ergometer at a heart rate corresponding to 65% of Pmax. Training intensity maintained at ≈90% of maximal heart rate | 6 weeks (5x/week) Dosage = 15 |
None | Muscle architecture | ||
| Muscle fibre area (μm2) | ↑ 8.3% (NS) | |||||||||
| Biopsy myofibrils (%) | ↓ 4.0% (p < 0.05) | |||||||||
| Capillary-to-fibre ratio (ALL) | ↑ 12.1% (p < 0.05) | |||||||||
| Capillary-to-fibre ratio: | ||||||||||
| A/A genotype | ↑ 25.0% (NS) | A/A vs. T/T (p < 0.05) | ||||||||
| A/T genotype | ↑ 12.6% (p < 0.05) | A allele carriers vs. T/T (p < 0.05) | ||||||||
| T/T genotype | ↓ 12.5% (NS) | |||||||||
| Capillary density (mm−2) | ↓ 5.5% (p < 0.05) | |||||||||
| Ventilatory changes | ||||||||||
| VO2max (mL/kg * min) | ↑ 8.5% (p < 0.05) | |||||||||
| Pmax (ergospirometry) (W) | ↑ 12.7% (p < 0.05) | |||||||||
| Walton et al., 2019 [41] | USA | Exercise (20); Male (4, 25%), Female (16, 75%) | 49.8 ± 2.3 * | Pre–post study | AET: participants performed 45 min sessions using a stationary cycle ergometer (at a target intensity corresponding to 65% of VO2max and ≈75–80% of maximum heart rate) | 12 weeks (3x/week) Dosage = 27 |
None | N/A | N/A | N/A |
| Alghadir et al., 2016 [42] | Saudi Arabia | Exercise (25); Male with T2D (25, 100%) | 48.8 ± 14.6 | RCT | Supervised AET: 50 min in intensity defined by heart rate (THR max; 60–70%) | 12 weeks (3x/week) Dosage = 30 |
None | N/A | N/A | N/A |
| Control (25); Male (25, 100%) | 48.7 ± 3.4 | Sedentary lifestyle | ||||||||
| Olstad et al., 2020 [34] | Norway | Pre–post study | Supervised heavy-load RET: it involved all major muscle groups. Gradual progression on the training loads was applied. Each session lasted ≈60 min. | 13 weeks (3x/week) Dosage = 39 |
5 One participant did not complete the study |
Muscle strength/
capacity |
N/A | |||
| Exercise healthy (18); Female (18, 100%) | 73.9 ± 5.7 | |||||||||
| Relative strength | Healthy: ↑ 32 ± 16% | |||||||||
| Osteoporotic: ↑ 31 ± 19% | ||||||||||
| Exercise osteoporotic (17); Female (17, 100%) | 78.0 ± 6.2 | |||||||||
The last two entries are from clinical populations. Data are presented as mean ± SD or ± SEM (*); number (n); hours (h); randomised controlled trial (RCT); resistance exercise training (RET); combined training (CT); aerobic exercise training (AET); high intensity interval training (HIIT); sedentary period (SED); electrical stimulation (ES); decrease (↓); not significant (NS); not available (N/A); repetition maximum (RM); lean body mass (LBM); cross sectional area (CSA); increase (↑); maximum training heart rate (max THR); maximal aerobic capacity (VO2max); maximal accumulated oxygen deficit (MAOD); voluntary repetition maximum (VRM); submaximal exercise respiratory exchange ratio (Submax RER); lactate threshold (LT); lactate threshold at 4 mmol/l (LT4); body weight (BW); fat free mass (FFM); absolute units (AU); intravenous failure (IV failure); Type 2 Diabetes (T2D); vastus lateralis (VL); quadriceps femoris (QF). Attrition: 1 A male participant was removed from analysis because of poor sample quality. 2 Dropouts and medical issues kept five older and two young participants out of the final analysis. 3 Ten subjects (four in the exercise group, six in the control group) could not complete the study. Reasons: difficulties of time commitment and loss of motivation. 4 Five young adults dropped out from the study. Reasons: (a) time constraints (n = 2), (b) medical unrelated to the study (n = 2), (c) and IV failure (n = 1). Three older adults dropped out. Reasons: (a) medical unrelated to the study (n = 1), (b) did not want to perform follow up testing (n = 1), and (c) completed sedentary-only portion (n = 1). 5 A compression fracture in the spine was attained during an accident in the squat exercise. Recovery of the patients was succeeded after 3 months of reduced loading.