Resistance exercise snacks as a workplace health intervention
Authors: Brandt Tom , Schwandner Christian Thomas Lothar , Schmidt Annette 
Published: September 2024

Introduction & Purpose
Although resistance training (RT) is essential to preserve musculoskeletal fitness and maintain a healthy, independent life into old age, only 10-30% of adults perform the recommended number of 2 RT per week, with women participating in even less RT (Bennie et al., 2016, 2018). As women have less skeletal muscle mass, experience an earlier strength loss, and a greater decline in muscle quality, RT appears especially beneficial for them (Doherty, 2001; Janssen et al., 2000). A novel approach to deal with common participation barriers (lack of time, limited access to equipment/facilities) are resistance exercise snacks (RES; Fyfe et al., 2022). Therefore, it was investigated whether RES is an efficient concept for the workplace health promotion (WHP) to facilitate RT in women and improve musculoskeletal fitness.
Methods
This pilot-study followed a prospective, controlled intervention design. Female employees with sedentary occupations doing RT on less than 2 days/week before study participation were included. Participants self-selected for intervention group (IG) or control group (CG). While the IG (N = 15, mean age 42.1 ± 11.1 years) completed 10 min of RES each working day for 12 weeks supervised by a trainer, the CG (N = 15, mean age 49.9 ± 9.7 years) maintained their habitual physical activity. Primary outcome was change in muscle mass (bioelectrical impedance analysis, SECA® mBCA515 scale). Secondary outcome was change in maximum isometric strength (Dr. WOLFF BackCheck® 617). Balance (Y-balance composite-score, Y-Balance test kit), cardiovascular fitness, (6-minute walking test), perceived health (minimum European health module), and general life satisfaction (general life satisfaction short scale) were assessed for exploratory purpose. Measurements were taken before and after the intervention. The difference in change between groups for muscle mass, strength, balance, and cardiovascular fitness was analyzed via mixed model ANOVA. For perceived health and general life satisfaction Wilcoxon test was applied to analyze within group changes.
Results
12 participants of IG and 14 of CG completed the study. Muscle mass improved significantly more in the IG (+.42 kg ± .54) compared to the CG (-.16 kg ± .51) (p = .01, ⴄ²p = .24). Strength did not change significantly between groups. Nevertheless, there was a trend for greater improvements in the IG compared to the CG for trunk extension, trunk flexion, and upper body push but not upper body pull. Regarding exploratory endpoints, no significant changes were found.
Discussion
Findings of the present study support the notion that training with light loads (< 30% of 1RM) effectively stimulate muscle protein synthesis if the intensity of effort is high. Higher training loads might be required to maximally recruit muscle fibers and induce optimal strength gains. For improvements in balance and cardiovascular fitness more specific training programs are required. Future studies should investigate what training stimuli are needed within RES (e.g., volume, load, frequency) to optimize improvements in musculoskeletal fitness and motivate participants in the long-term applying randomized controlled intervention designs.
Conclusion
RES is an efficient approach for the WHP to improve muscle mass in inactive women with sedentary occupations.
References
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Bennie, J. A., Pedisic, Z., van Uffelen, J. G. Z., Charity, M. J., Harvey, J. T., Banting, L. K., Vergeer, I., Biddle, S. J. H., & Eime, R. M. (2016). Pumping iron in Australia: Prevalence, trends and sociodemographic correlates of muscle strengthening activity participation from a national sample of 195,926 adults. PLoS ONE, 11(4), Article e0153225. https://doi.org/10.1371/journal.pone.0153225
Doherty, T. J. (2001). The influence of aging and sex on skeletal muscle mass and strength. Current Opinion in Clinical Nutrition & Metabolic Care, 4(6), 503–508.
Fyfe, J. J., Hamilton, D. L., & Daly, R. M. (2022). Minimal-dose resistance training for improving muscle mass, strength, and function: A narrative review of current evidence and practical considerations. Sports Medicine, 52(3), 463–479. https://doi.org/10.1007/s40279-021-01605-8
Janssen, I., Heymsfield, S. B., Wang, Z., & Ross, R. (2000). Skeletal muscle mass and distribution in 468 men and women aged 18–88 yr. Journal of Applied Physiology, 89(1), 81–88. https://doi.org/10.1152/jappl.2000.89.1.81