Effects of 8 Weeks of Balance Training, Virtual Training, and Combined Exercise on Lower Limb Muscle Strength Balance, and Functional Mobility Among Older Men: A Randomized Controlled Trial: Letter to the Editor

Dear Editor:

We have read the recently published article, “Effects of 8 weeks of balance training, virtual training, and combined exercise on lower limb muscle strength balance, and functional mobility among older men: a randomized controlled trial” by Sadeghi et al ¹⁰ with utmost interest. We believe that the authors have made a considerable contribution through this work. The authors have highlighted the major risk factors associated with fall and their impact on older adults as well as mentioning recent researches and guidelines on fall prevention practice among community-dwelling adults. We gained knowledge after reading this article but noticed some points that need more clarification from the authors.

First, the authors compared the effect of balance training, virtual training, or combined exercise relative to waitlist control group among older adults; however, the authors could have stated the study design as “A randomized controlled waitlist trial” rather than “A randomized controlled trial.”^1,3

In the Abstract and Introduction section, the authors have used a one-tailed hypothesis that states that 8 weeks of balance training, virtual reality training and combined exercises (MIX) would give better results in improving fall risk in comparison with other treatment groups. Other than that, the authors specifically mentioned variables such as muscle strength, balance, and functional mobility in the title itself (with no mention of fall risk). Hence ”muscle strength, balance and functional mobility” should be used in hypothesis instead of ”fall risk.” In our view, the hypothesis is completely biased for the MIX group as the authors presumed prospectively that it is the MIX group that would show better improvement rather than other groups. We would suggest the hypothesis should be 2-tailed, eg, 8 weeks of treatment through MIX show significant difference in improving muscle strength, balance, and functional mobility in comparison to a control group. ⁷

In the Methods, the authors describe sample size calculation using G*Power (Version 3.1.6); however, it is not clear which statistical tests have been used to determine the sample size, ie, whether sample size was calculated using test family F-tests or t tests. If we consider F-tests as the test family as the number of groups are >2, then which statistical test has been used to estimate the sample size. If analysis of variance: repeated measures, between factors would be used, then the required sample size comes out to be 248 (62 in each group) (Figure 1) and if ANCOVA: fixed effects, main effects and interaction would be used with minimum numerator df as 1, then the calculated sample size again comes out to be 248 (62 in each group) (Figure 2). By both methods, the estimated sample size is different from the sample size quoted in the study.

Figure 1.

Sample size estimation through G*Power using ANOVA: repeated measures, between factors. ANOVA, analysis of variance.

Figure 2.

Sample size estimation through G*Power using ANCOVA: fixed effects, main effects and interaction. ANCOVA, analysis of covariance.

In the Methods section, the selection criteria have not been clearly stated. Ideally, the authors should take some baseline measurement of a valid and reliable tool such as Berg Balance Scale (BBS) or Tinetti’s Performance-Oriented Mobility Assessment scale (POMA) to match all participants at baseline. There should be some score, eg, if the fall risk of the subjects has to be measured then the subjects could have a baseline score of 31 to 45 in BBS and <19 in POMA, which demonstrates a greater risk of fall among adults.^4,8 In the exclusion criteria, it is appreciated that the authors excluded neurological or cardiovascular impairments, but it should also be kept in mind that, at this age, older adults might face arthritic disorders or other musculoskeletal conditions. Hence, all musculoskeletal conditions affecting lower limb or surgeries in the past 6 months should be excluded, and not only fractures and lower limb joint replacements. ¹²

Regarding primary outcome measures, we appreciate that the authors presented all the outcome measures very well, including the reliability and validity of each outcome. However, we would like to suggest that the authors include the cut-off values for knee flexor strength for isokinetic dynamometer, which is 0.69 to 0.89 Nm/kg (male) and 0.46 to 0.89 Nm/kg (female) along with the knee extensor strength as the study was conducted to provoke improvement in both knee flexion and extension strength. ¹¹

We also appreciate that author has clearly discussed the results of the study; however, the tables provided in the Appendix should be included in the article itself for clearer interpretation of the results.

In the Discussion section, the authors could represent the result in terms of clinical significance by mentioning minimally clinical important difference (MCID) values for different outcome measures, eg, Timed Up and Go test has an MCID value of 3.4 seconds, single-leg stance has an MCID value of 22.1 seconds, 10-m walk test has an MCID value of 0.22 and 0.23 m/s and isokinetic dynamometer has an MCID value of 24% in peak torque and 20% in work in knee extensor and flexor muscles strength.^2,5,6,9

The author’s work is highly commendable, and the accuracy of the study will be improved if the issues stated above are taken into account. It will be more advantageous for readers and researchers to have further research guidance.

Regards,
Nidhi Sharma, BPT, MPT
Department of Neurological Physiotherapy, Maharishi
Markandeshwar Institute of Physiotherapy and Rehabilitation,
Maharishi Markandeshwar (Deemed to be University), Mullana,
Ambala, Haryana, India

Parveen Kumar, BPT, MPT, PhD
Pal Physiotherapy Clinic, Pal Healthcare,
Ambala City, Haryana, India

Simranjeet Kaur, BPT, MPT
Department of Musculoskeletal Physiotherapy, Maharishi
Markandeshwar Institute of Physiotherapy and Rehabilitation,
Maharishi Markandeshwar (Deemed to be University), Mullana,
Ambala, Haryana, India

Nidhi Sharma, BPT, MPT, PhD
Department of Neurological Physiotherapy, Maharishi
Markandeshwar Institute of Physiotherapy and Rehabilitation,
Maharishi Markandeshwar (Deemed to be University), Mullana,
Ambala, Haryana, India