The effects of blood flow restriction training during low intensity online resistance training with older adults

Abstract

[Purpose]

Blood flow restriction (BFR) training involves limiting blood flow to specific areas, enabling low-intensity exercise to mimic high-intensity workouts. This study explored the effectiveness of combining BFR with online exercise classes to improve strength and functionality in older adults.

[Methods]

Over ten weeks, men and women, N = 41 with 22 BFR and 19 control (CON), (mean age = 70 ± 6.2) participated in Zoom sessions twice a week. Strength in the hamstrings and quadriceps was assessed using a dynamometer, while functionality was tested with the 30-second sit-to-stand, 8-foot timed up-and-go, and 30-second calf raise tests.

[Results]

Both the BFR and CON groups showed improvements in muscle strength and lower extremity functionality. However, the BFR group achieved greater gains, mainly in functional performance.

[Conclusion]

The observed preliminary evidence suggests that BFR augment the effectiveness of low-intensity exercise by providing an additional physiological stimulus without increasing mechanical load. This study highlights a novel, accessible, and practical strategy for improving functional mobility in aging populations, particularly for individuals who may be unable or unwilling to engage in higher-intensity training. ClinicalTrials.gov: NCT06724393.

INTRODUCTION

The average age of the population is rising, with ten percent of the world being made up of people over the age of sixty-five [1]. This demographic shift places a strain on the healthcare system, contributing to higher rates of disease diagnoses, increased falls, and a rise in medical costs. Although age-related physiological decline cannot be entirely prevented, its progression can be delayed and mitigated through targeted interventions [2].

Physical activity is one of the most effective strategies for its potential to increase life expectancy and promote healthy aging. Merely five hours of light physical activity a week can reduce mortality rates by approximately 30% in comparison to those who live a sedentary lifestyle [3]. In addition to promoting longevity, regular exercise significantly lowers the risk of cardiovascular disease, cancer, and other life-threatening conditions [3].

Resistance training (RT) has proven to be an effective method for preventing and treating musculoskeletal disorders, which become prevalent as we age [4]. It plays a critical role in maintaining or improving bone mineral density, muscle mass, and strength which are essential adaptations for reducing fall risk, preserving functional independence, and decreasing reliance on healthcare services [4,5]. Achieving these benefits requires surpassing the loads typically encountered in typical daily activities, which unfortunately, can be challenging for some older adults. Barriers such as fear of injury, discomfort in gym environments, and limited accessibility contribute to low participation rates, with fewer than 15% of older adults engaging in RT at least twice per week [6].

Blood flow restriction (BFR) is a method to reduce perfusion to an area of the body, which allows low intensity exercise to induce high intensity benefits. BFR involves the application of adjustable cuffs or elastic bands to the proximal portion of a limb, partially restricting arterial inflow while substantially limiting venous outflow. This creates a hypoxic, metabolically stressful environment within the muscle7. Typically, weight training requires loads of 60-80% of a 1-repetition maximum (1RM) to be effective. However, it has been shown that muscular strength and function can improve at a lower 1RM percentage of approximately 20-30% with BFR, thus exceptionally beneficial for older individuals with contraindication to heavy weight training or fear of injury [7]. Takarada and colleagues showed that low intensity RT exercise with 100 mmHg occlusion of blood flow, resulted in significant increase in lactate accumulation due to reduced clearance rate [8]. The resulting lactate buildup causes muscle swelling, triggering mitogen-activated protein kinase pathways, stimulating muscle protein synthesis, leading to greater muscle hypertrophy. Additionally, the hypoxic environment accelerates the recruitment of type II muscle fibers by necessitating earlier reliance on anaerobic metabolism, even at low exercise intensities [9,10]. These adaptations are particularly beneficial for older adults, especially those experiencing sarcopenia or who are unable to tolerate high mechanical loads.

Furthermore, BFR has been studied for its ability to stimulate hormone release in response to increased metabolic stress during exercise. Increased metabolic stress stimulates the release of anabolic and vasoactive hormones, including growth hormone, insulin-like growth factor-1, vascular endothelial growth factor, and norepinephrine, all of which contribute to muscle remodeling, vascular adaptation, and overall physiological resilience [9,11,12]

BFR is a convenient and accessible method of training that can be easily integrated in home-based settings. According to Mullen and Whaley, individuals aged 55-64 and those over 65 are the least likely to be gym members [13]. There is a pattern seen in older adults of apprehensiveness to leave their home due to various factors including weather conditions, difficulties with public transport or being too accustomed to their environment. Home-based exercise interventions, therefore, offer a valuable opportunity to improve adherence and long-term engagement in physical activity.

Despite growing interest in telehealth interventions, the integration of BFR into online exercise programs remains underexplored. Most existing studies have focused on supervised, in-person protocols, and many utilize specialized equipment that limits feasibility in home settings [14]. This gap highlights the need for scalable, accessible interventions that combine the benefits of BFR with remote delivery methods

The aim of this study was to determine whether 10 weeks of online low intensity resistance training (LIRT) for older adults results in greater improvements in strength and functionality when using BFR straps on the proximal thigh compared to LIRT alone. It is hypothesized that the BFR group will have better outcomes in all the test batteries.

METHODS

This study employed a randomized, parallel-group clinical trial design and was registered on ClinicalTrials.gov (NCT06724393). Participants were recruited through poster advertisements distributed to community and fitness centers in the Montreal area. Participants were randomized using a computer-generated stochastic sequence generated via a random number generator. Blinding of outcome assessors was not feasible because of staffing limitations and the nature of the intervention. Consequently, all outcome assessments were conducted by investigators who were aware of participants’ group allocation. In total, 47 participants responded and passed eligibility, as demonstrated in Figure 1. Inclusion criteria required participants to be 60 years of age or older, have a basic understanding of English, access to Zoom, be able to attend three in-person testing sessions, and have no contraindications to exercise. Exclusion criteria were varicose veins, a chronic disease (such as multiple sclerosis, fibromyalgia, Parkinson’s disease etc.) and/or the occurrence of a stroke in the last six months. These criteria were assessed using a self-reported form that needed to be filled out prior to receiving the consent form. Once consent was signed, their self-reported questionnaire was reviewed in detail to confirm the absence of underlying health conditions that would contraindicate participation. Regarding medication use, detailed reporting of individual medications was not included, as participants with chronic conditions or severe disease were excluded from participation. Any reported medications were not expected to meaningfully influence physical performance or training capacity within the context of the present study.

Figure 1. Participant CONSORT flow diagram.

47 participants were recruited and successfully passed all eligibility criteria. By post-testing, 41 participants completed the entirety intervention. Reasons for withdrawal are outlined.

Information regarding participants’ prior exercise experience was collected informally through discussion during the testing sessions which demonstrated that the cohort appeared heterogeneous, comprising of individuals with previous resistance training experience, participants who regularly engaged in structured exercise classes, and individuals with little to no prior structured exercise experience.

The mean age of participants was 70 ± 6.2, with 11 men and 30 women making a total of 41 (with 22 BFR and 19 control (CON)) participants who completed post testing. Reasons for withdrawal and further descriptions regarding participants, such as weekly physical activity levels are summarized in Figure 1 and Table 1 respectively.

Table 1.

Characteristics of participants separated by group; BFR or CON. No statistical difference between two groups was determined via independent t-test

Characteristics	BFR	CON	T-test (p value)
Final Sample Size	22	19
Males Females	6	5
	16	14
Age	68 ± 7.0	72 ± 4.5	0.451
Height (cm)	169.6 ± 8.6	172.2 ± 7.1	0.499
Weight (kg)	74.5 ± 14.1	77.3 ± 15.5	0.250
Exercise level (hours/week)	3 ± 0.5	2.5 ± 1	0.062

Protocol

The intervention consisted of ten weeks of online classes held twice a week via Zoom. All sessions were recorded, giving participants the flexibility to complete the classes at their convenience if attending live sessions was not possible. Participants who completed the class using the recording were asked to send an email confirmation. For those who attended the live session, attendance was documented at the beginning of the class. To ensure participant safety, a second individual in addition to the instructor was present online during all sessions to respond in the event of an emergency or adverse event; however, no such incidents occurred during the study period.

Program

For the first 5 weeks of classes, the program consisted of three warm up movements, seven RT exercises and a cool down which focused on stretching the muscles worked. The warm-up included 10-15 seconds of arm circles and ankle rotations in both directions, 10 repetitions of trunk twists and a 30 second march in place. The LIRT movements included 3 × 12 squat to overhead press, 3 × 12 deadlift to bicep curls, 3 × 15 lateral raises, 3 × 10 per leg of lunges, 3 × 15 glute bridges, 3 × 10 dead bug and 3 × 15 calf raises. Cool down included standing hamstring, quadricep, triceps, shoulder and calf stretch and a full body stretch reaching for the toes with a 10 second hold. The last 5 weeks of the intervention, the squat to overhead press and deadlift to bicep curl was increased to 15 repetitions. A front raise was added to the lateral raise. The glute bridge was progressed to a single leg for 3 × 12 each leg. Lastly the calf raises were increased to 20 repetitions. All exercises were performed using body weight only. The changes made at the mid-point of the intervention are illustrated in a flow diagram in Figure 2.

Figure 2. Flow diagram of program changes from weeks 1-5 and weeks.

Testing

In person testing was completed pre (week 0), mid (week 4-6) and post intervention (week 11). At the first testing session, participants who were randomized in the BFR group were given their adjustable BFR straps as well as their individual tightness according to a perceive pressure scale. A rating of 0 indicated minimal pressure on the limb, whereas a rating of 10 represented pressure reaching the point of pain. As BFR pressure was determined subjectively, this approach reflects a more practical and applied method of BFR application in real-world settings. A tightness rating of 7–8 was considered appropriate and is consistent with previous literature. Ancieto et al. reported that a perceived exertion of approximately 7 out of 10 corresponds to ~73% of arterial occlusion pressure in the lower extremity15,16. The testing included the following assessments designed to measure both functional and absolute strength:

- 30 second sit to stand (STS): Participants were asked to perform as many STS as possible in 30 seconds. The test was done on a standard chair – 18 inches high – with no wheels and pushed up against the wall. If the participant failed to tap the chair during their sit, the repetitions did not count.

- 8 ft timed up and go (TUG): Participants were asked to sit on a stable chair, walk 8 ft around a cone and sit back down as fast as they could without running.

- Strength test of the hamstrings and quadriceps muscles: The Biodex 4 pro and HUMAC dynamometers were used to test the strength of the lower extremity. Participants were asked to use their dominant leg to complete the test. Only one limb was tested in order avoid using a leg with knee or hip replacements. The test consisted of completing full flexion and extension of the knee three times at 60 degrees/second (d/s), 120 d/s and 180 d/s. The first speed of 60 d/s was completed twice to control for the learning curve with the best outcome used for analysis. In between each speed was a mandatory 90 second rest.

- Calf raise senior (CRS): Participants were asked to perform as many calf raises as possible in 30 seconds. Prior to starting, they were asked to reach their maximum height. A paper was placed at their respective height; if during the assessment, they failed to tap the paper, the repetition did not count. Participants were advised to avoid bending the knees to ensure the calf muscles were used rather than the upper leg.

Following the intervention, participants were sent a survey to assess their satisfaction with online training. The intention was to better understand the effectiveness of a telehealth intervention from the subjective view of the participants. The survey was optional but encouraged and all information was anonymous.

Survey

During the final week of the intervention, all participants were invited to complete a Google Forms questionnaire to provide feedback on their experience. The questionnaire was distributed electronically, and all survey questions are presented in Table 4.

Table 4.

Participant experience questionnaire administered during the final week of the intervention. The questionnaire was distributed electronically using Google Forms to obtain participants’ feedback on their experience

Question No.	Survey Question	Response Format
1	Based on the 10 weeks, how did you find your experience taking the class online?	Open-ended
2	Considering your experience with the resistance training class, how likely would you be to recommend it to a friend?	11-point Likert scale (0 = Very unlikely; 10 = Very likely)
3	Did you find the class difficult to follow? If yes, please provide an example of when you felt this way.	Yes/No with open-ended follow-up
4	What were some of the barriers you experienced during this class?	Open-ended
5	What was your method of training during this intervention?	Multiple choice (Live, Recording, or Hybrid)
6	Given the choice between live classes and recordings, which would you prefer? Please explain your choice.	Preference selection with open-ended explanation

Statistics

All data were analyzed using IBM SPSS Statistics v.29.0.2.20. Normality of the variables was tested with the Shapiro-Wilk test and appropriate descriptive statistics were calculated. Outliers were determined and removed using a Grubb’s test with only one participant removed from the CON group for functionality performance tests. Comparisons between the BFR and CON groups were performed with a two-way ANOVA. Following significant time effects or group × time interactions, Bonferroni-adjusted pairwise comparisons were performed to compare outcomes between pre-, mid-, and post-intervention assessments. The significance level was set 0.05 for all tests.

RESULTS

The 30s STS showed significant difference between groups (p = 0.004), with the BFR group improving from pre to mid, mid to post, and pre to post (p < 0.001, 0.005 and < 0.001 respectively), The CON group had no change from pre to mid (p = 1.0) but improved significantly by week 10 (p < 0.001). ANOVA analysis confirmed a significant effect of time across the intervention (p < 0.001), suggesting overall improvement regardless of group.

The CRS test demonstrated significant difference between groups (p = 0.049), with improvements in both CON and BFR, but greater outcomes with BFR (from pre to post, CON p = 0.005, BFR p < 0.001). ANOVA showed a significant time effect (p < 0.001).

The 30s STS and CRS results are illustrated in Figure 3 and 4 respectively.

Figure 3. Change in 30s STS from pre-, mid- to post.

Stars indicate significant change within-group changes, while crosses denote significant between group differences (p < 0.05). Error bars represent the standard error at each time point.

Figure 4. Change in 30s CRS from pre-, mid- to post.

Stars indicate significant change within-group changes, while crosses denote significant between group differences (p < 0.05). Error bars represent the standard error at each time point.

The TUG test, presented in Figure 5, demonstrated no significant difference between groups (p = 0.380). The BFR group decreased their time by 5.8% from pre to post despite no statistical significance (p = 0.102) while the CON group showed no significant change at any time point (p = 1.0). ANOVA indicated no significant time effect (p = 0.071).

Figure 5. Change in TUG from pre-, mid- to post.

Error bars represent the standard error at each time point.

Upper leg strength – flexion 60 d/s showed no significant difference between groups (p = 0.182) or time effect (p = 0.172). Both groups improved slightly, however no statistical significance was reached for any time point.

Upper leg strength – extension 60 d/s showed no significant difference between groups (p = 0.898). However, the BFR group improved significantly from pre to mid (p = 0.014) and pre to post (p = 0.007), but not mid to post (p = 0.491). The CON group significantly improved only from pre to post (p = 0.008), with no significant change from pre to mid (p = 0.071) or mid to post (p = 0.211). ANOVA for quadriceps strength showed a significant time effect (p < 0.001).

Hamstring to quadriceps ratio was calculated using the dynamometer data at 60 d/s. There was no significant difference between groups or through time (p = 0.424 and 0.386 respectively)

A fast slow ratio was calculated using the data from 60 d/s and 180 d/s for both flexion and extension. Flexion showed no group or time differences (p = 0.295 and 0.215 respectively), however a pairwise comparison indicated improvement for the BFR group by post-testing (p = 0.057). Both groups still improved, BFR group by 7.6% and CON by 2.8% by week 10. For extension, no significant difference between groups was observed (p = 0.755), however trends towards difference across time was observed (0.082). Both groups improved over the course of the intervention, with the BFR group demonstrating a 5.7% increase compared to a 2.7% increase in the CON group.

Effect sizes at post-intervention were small across all conditions (d = 0.10–0.36) except for Fast: Slow ration for knee flexion (d = 0.7). Strength outcomes and specific effect sizes are shown in Table 2 and 3.

Table 2.

Strength data at all three speeds for each muscle action with group*time p-values and post intervention effect size

Speed	Muscle Action	Time	BFR (Mean (N-m) ± SD)	CON (Mean (N-m) ± SD)	p-value (Group × Time)	Cohen’s d
60°/s	Extension	Pre	109.5 ± 36.9	83.4 ± 28.8	p-value between baselines = 0.281
		Mid	114.1 ± 34.4	103.9 ± 27.4
		Post	116.7 ± 32.3	108.4 ± 31.7	0.898	0.26
	Flexion	Pre	73.5 ± 28.5	67.5 ± 22	p-value between baselines = 0.525
		Mid	77.0 ± 28.5	69.7 ± 18.6
		Post	75.0 ± 26.9	72.7 ± 20.3	0.182	0.10
120°/s	Extension	Pre	76.5 ± 31.3	69.7 ± 25.7
		Mid	85.7 ± 30.2	78.2 ± 23
		Post	87.7 ± 27	80.6 ± 27.6	0.980	0.26
	Flexion	Pre	55.1 ± 24	42.7 ± 18.3
		Mid	61.4 ± 25.2	56.8 ± 13.6
		Post	62.2 ± 22.9	58.4 ± 15.2	0.938	0.20
180°/s	Extension	Pre	65.4 ± 25.6	59.4 ± 21
		Mid	71.8 ± 24.1	64.8 ± 19.9
		Post	72.8 ± 22.5	67.8 ± 24	0.787	0.21
	Flexion	Pre	52.4 ± 21.7	47.7 ± 18.2
		Mid	55.9 ± 22.5	50.8 ± 13.4
		Post	57 ± 19.7	51.9 ± 13.5	0.987	0.31

Table 3.

H:Q ratio from 60degrees/second strength data and Fast:Slow ratio using slowing and fastest speed with group*time p-values and post intervention effect size

Variable	Time	BFR (Mean ± SD)	CON (Mean ± SD)	p-value (Group × Time)	Cohen’s d
H:Q Ratio	Pre	0.670 ± 0.08	0.701 ± 0.12
	Mid	0.670 ± 0.10	0.680 ± 0.11
	Post	0.640 ± 0.11	0.680 ± 0.11	0.493	0.36
Fast:Slow Ratio Flexion	Pre	0.712 ± 0.08	0.70 ± 0.12
	Mid	0.72 ± 0.08	0.73 ± 0.06
	Post	0.77 ± 0.08	0.72 ± 0.06	0.295	0.70
Fast:Slow Ratio Extension	Pre	0.596 ± 0.08	0.604 ± 0.06
	Mid	0.630 ± 0.07	0.621 ± 0.06
	Post	0.630 ± 0.06	0.620 ± 0.07	0.778	0.15

DISCUSSION

The key findings of this study are that older adults who wore BFR straps during LIRT demonstrate greater improvements in both strength and functionality. While previous research has examined the effectiveness of BFR, this study brings novelty due to the combined impact of an online intervention specifically on older adults, which has not been thoroughly explored.

This intervention was conducted online to overcome common barriers to in-person activities, such as limited access to public transportation, lack of confidence in a gym setting, and meteorological conditions. Virtual classes provided a safer and comforting option for participants17. In a post-intervention survey, 38 of the 41 participants responded to questions regarding their satisfaction towards the course. When asked “have you experienced any positive/negative changes in your activities of daily living?”, participants reported altered confidence and enjoyment through different answers such as “easier going up and down the stairs” and “I approach my daily tasks with more enthusiasm and energy”. Overall attendance was high, with a mean adherence rate of 98.2% across the ten-week program, including participation via both live and recorded classes. When compared to online fitness programs in Canada, which typically report attendance rates of 50–70%, the adherence observed in this study exceeds the expected average [17].

Beyond the subjective feedback received, results in functional performance demonstrated greater improvements in the BFR group. The functional performance measures used were chosen as they represent key determinants of mobility, independence, and overall physical function in older adults [20-22]. As seen in Figure 3, the 30s STS showed a steady increase in repetitions in the BFR group, with a significant group difference by the end of the intervention. Similarly, the CRS test, presented in Figure 4, showed an increase in performance by ten weeks in both groups with a statistical difference between groups, with the BFR group outperforming the CON. For the TUG, the CON group showed no improvement, as displayed in Figure 5. In contrast, the BFR group demonstrated progress, reducing their time by 0.3 seconds by the end of the 10 weeks. For clinically meaningful changes in the TUG test, a reduction of approximately 0.8–1.4 seconds is generally considered necessary. However, even smaller, non-significant improvements may still be clinically relevant in this population, as gait speed typically declines with age, and each additional second required to complete the TUG reflects a meaningful reduction in functional mobility. Additionally, the intervention focused on strength with little to no changes of directions or speeds, thus an improvement in TUG may suggest better balance and mobility in lower extremity [24].

When analyzing the strength of the lower extremity measured using a dynamometer, the extension showed significant improvements in both groups. However, the improvements in flexion were less pronounced. It is important to consider the roles of type I and type II muscle fibers in strength development, where the hamstrings consist dominantly of Type II [25]. Type I muscle fibers are primarily engaged during lower-intensity activities that require sustained muscle contractions, applicable to the online class with more focus on volume than power [26-28]. During resistance exercise performed at submaximal loads (< 70% 1RM), high-threshold motor units containing type II muscle fibers are generally not recruited at the onset of a set. Instead, motor units are recruited according to Henneman’s size principle, with low-threshold type I motor units activated first and progressively larger, higher-threshold type II motor units recruited only as force requirements increase or fatigue develops. Consequently, low-load resistance exercise that is not performed close to muscular failure may result in limited recruitment of type II muscle fibers [28,29]. Therefore, the improvements in quadriceps performance observed by week five in the BFR group may be attributable to the application of BFR; however, this anterior chain–dominant adaptation may also help explain the relatively limited improvements observed in hamstring strength. An increase in strength after just five weeks of LIRT is a notable finding, suggesting that older adults can achieve meaningful improvements in strength over a relatively short timeframe [30,31]. Additionally, aside from exercises such as the glute bridge, the training program was largely quad-dominant (e.g., squats, lunges), as these movements were more practical to implement in a home-based setting. This may have limited the overload to the hamstrings and, consequently, their progression. Furthermore, the stimulus of the training program differed considerably from that of the testing protocol. Type II muscle fibers generate greater force but fatigue rapidly, and are primarily activated during high-intensity, short-duration activities, such as maximal strength testing on a dynamometer. This may help explain why the BFR group did not demonstrate additional improvements in hamstring strength, while still showing greater improvements in quadriceps strength [30,32].

It was hypothesized that hamstring to quadriceps (H:Q) ratio would remain unchanged given the absence of measurable improvements in hamstring strength. Ideally, it is desired for this ratio to increase as a 0.1-unit reduction in H:Q ratio fosters the probability of falling by a factor of 1.30 [33]. The fast:slow ratio is a representation of how efficiently a muscle can maintain its strength at different speeds. Typically, peak high-velocity testing is performed at 240 d/s in a younger population with a meaningful improvement described as a 6-11% increase in torque. The present study used a slightly lower velocity of 180 d/s which represents a high contraction speed in older adults and thus remains relevant for assessing fast-twitch muscle function. Notably, the BFR group demonstrated a 6.8% increase in torque within just five weeks and maintained this improvement by week 10, aligning with this proposed benchmark. However, this comparison should be interpreted with caution, as the 6-11% threshold is based on 240 d/s testing, and 180 d/s may not capture peak velocity-dependent adaptations to the same extent [34].

Prior training status and inter-individual variability may have influenced the magnitude and consistency of the observed adaptations following BFR training. Although baseline characteristics were comparable between groups, participants likely entered the study with differing levels of neuromuscular efficiency, habitual physical activity, and responsiveness to resistance exercise, all of which can moderate training-induced adaptations. Thus, individuals with lower initial training status may have experienced relatively greater gains due to a higher capacity for improvement, whereas more trained participants may have exhibited attenuated adaptations consistent with a reduced adaptive reserve. In addition, inherent biological variability in factors such as muscle fiber composition, vascular responsiveness, and perceptual tolerance to ischemic stress may have contributed to between-subject differences in training response. Still, it is important to highlight that baseline demographic characteristics were comparable between groups, with no meaningful differences detected using t-tests (all p-values reported in Table 1), supporting the internal validity of the group comparisons. However, these sources of heterogeneity may partly explain the variability observed in outcomes and should be considered when interpreting the magnitude and generalizability of the effects of BFR training in the present study.

Safety Considerations

To ensure safety, the application of the BFR bands was demonstrated to the participants at their first testing session and they were asked to practice taking them on and off at the right placement. Check-ins were done twice weekly via email, before every class, to ensure there were no injuries or difficulties following the course online. The participants were asked to give their address, phone number and emergency contact to the primary investigator before the start of the study in case 9-1-1 needed to be called during a session. Lastly, the instructor had an additional member of the research team logged onto the Zoom call in case of any emergency.

The main limitation of this study was the use of two different lower-limb dynamometers due to equipment malfunction during post-testing. Specifically, 16 of 41 participants were assessed using the HUMAC NORM system, while the remainder were tested on the Biodex System 4 Pro. Although previous work by Alvares et al. [34] reported no statistically significant differences in performance outcomes between these two systems (p > 0.05), that study was conducted in young adults and compared the Biodex system to Cybex equipment rather than the HUMAC NORM. While existing evidence suggests acceptable agreement between similar isokinetic dynamometers under standardized testing conditions, the possibility of residual inter-device variability cannot be excluded. This introduces a potential source of measurement heterogeneity that may have modestly affected between-subject comparisons and should be considered when interpreting the findings.

Another limitation of this study is the relatively modest sample size which may have limited the statistical power to detect small between-group differences, particularly for some strength-related outcomes. Although significant improvements were observed in several functional measures, the absence of significant differences in certain outcomes should not be interpreted as evidence of no effect, but rather as potentially reflecting limited power to detect smaller effects. Future studies involving larger cohorts are warranted to confirm these findings and provide more precise estimates of the effects of blood flow restriction training in older adults.

In addition, no formal correction for multiple comparisons was applied. While primary outcomes were specified a priori, several secondary analyses were exploratory in nature. Therefore, the risk of Type I error may have been increased, and significant findings from exploratory analyses should be interpreted with appropriate caution. These secondary analyses were intended to provide preliminary insights and generate hypotheses rather than serve as definitive evidence of efficacy.

Lastly, this study explored practical-BFR application and therefore, no objective comparison to pneumatic equipment was completed for pressure occlusion measurements. Although this translates well into real-world settings, this is a notable limitation as it is not comparable to previous BFR studies.

Conclusion

In conclusion, BFR training resulted in statistically significant improvements in the CRS and 30s STS tests. However, the majority of between-group comparisons did not reach statistical significance, indicating that the original hypothesis was only partially supported. These findings should be interpreted in light of the limited sample size and the small effect sizes observed, which may have reduced statistical power to detect differences across all functional outcomes. Further research with larger cohorts and optimized training protocols is warranted to clarify the potential role of BFR in improving functional performance in older adults. Still, our findings suggest that BFR when combined with resistance training may have meaningful clinical relevance beyond the observed improvements in isolated strength and performance measures. Although the magnitude of change in some outcomes was modest, even small increases in muscular strength and functional capacity can be important in populations where baseline functional reserve is limited or where age- or disease-related declines in neuromuscular performance are present. Improvements in lower-limb strength and task-specific performance are particularly relevant to activities of daily living that rely on repeated submaximal efforts, such as rising from a chair, climbing stairs, and maintaining balance during gait transitions. Given that these tasks are often constrained by relative rather than maximal strength, the observed adaptations may plausibly translate into improved ease and safety during daily functional activities, particularly in individuals operating near functional thresholds. However, as the present study was conducted in a relatively healthy cohort, the extent to which these changes translate into clinically meaningful improvements in independence or disability prevention in more impaired populations remains to be directly established. In future studies, extending the intervention beyond ten weeks may offer a more comprehensive understanding of the longterm benefits of BFR [35]. A longer timeframe may allow for observation of adaptations at a deeper physiological level, offering a clearer picture of how BFR contributes to muscle growth, endurance, and overall physical health.