Changes in Muscle Mass and Strength During Follow-Up After One-Year Resistance Training Interventions in Older Adults.

ABSTRACT: Mertz, KH, Reitelseder, S, Rasmussen, MA, Bülow, J, Højfeldt, G, Jensen, M, Hjulmand, M, Lindberg, J, Kramer, MU, Bechshøft, R, and Holm, L. Changes in muscle mass and strength during follow-up after one-year resistance training interventions in older adults. J Strength Cond Res 37(10): 2064-2070, 2023-The aim of this study was to investigate if home-based resistance training compared with center-based resistance training was associated with better preservation of muscle mass and strength in older individuals, 6 months after the interventions ended. One hundred four healthy older individuals (>65 years) who had completed 1 year of either home-based light-intensity training with daily whey protein supplementation (LITW), center-based heavy resistance training with whey protein supplementation (HRTW), or daily whey protein supplementation alone (WHEY) returned for follow-up measurement 6 months after the interventions. Measures of muscle mass, strength, and power were assessed at the end of intervention as well as at follow-up. Furthermore, we compared changes in these parameters between subjects who continued resistance training (≥1 weekly training session) during follow-up (CONT) with those who stopped (STOP). Resistance training continuation during follow-up did not differ between HRTW and LITW (41 vs. 41%, P = 1.0) but was higher for both groups compared with WHEY (18%, P = 0.04-0.05). However, no between-group differences were observed between LITW/HRTW/WHEY in changes in muscle mass, strength, or power during follow-up. STOP was associated with a poorer preservation of quadriceps cross-sectional area compared with CONT (-1.7 cm 2 [-0.4 to -3.0], P = 0.01, effect size: 0.79). No effect of training continuation was observed on changes in muscle strength and power. In conclusion, maintenance of muscle mass and strength is not superior after home-based resistance training compared with center-based training. However, training continuation seems crucial for the maintenance of muscle mass, irrespective of the training intervention.

Influence of between-limb asymmetry in muscle mass, strength, and power on functional capacity in healthy older adults.

PURPOSE: Numerous daily tasks such as walking and rising from a chair involve bilateral lower limb movements. During such tasks, lower extremity function (LEF) may be compromised among older adults. LEF may be further impaired due to high degrees of between-limb asymmetry. The present study investigated the prevalence of between-limb asymmetry in muscle mass, strength, and power in a cohort of healthy older adults and examined the influence of between-limb asymmetry on LEF. METHODS: Two hundred and eight healthy older adults (mean age 70.2 ± 3.9 years) were tested for LEF (400 m walking and 30-seconds chair stand). Furthermore, maximal isometric and dynamic knee extensor strength, leg extensor power, and lower limb lean tissue mass (LTM) were obtained unilaterally. RESULTS: Mean between-limb asymmetry in maximal muscle strength and power ranged between 10% and 13%, whereas LTM asymmetry was 3 ± 2.3%. Asymmetry in dynamic knee extensor strength was larger for women compared with men (15.0 ± 11.8% vs 11.1 ± 9.5%; P = .005) Leg strength and power were positively correlated with LEF (r2  = .43-.46, P < .001). The weakest leg was not a stronger predictor of LEF than the strongest leg. Between-limb asymmetry in LTM and isometric strength was negatively associated with LEF (LTM; r2  = .12, P = .005, isometric peak torque; r2  = 0.40, P = .03.) but dynamic strength and power were not. CONCLUSION: The present study supports the notion that in order to improve or maintain LEF, healthy older adults should participate in training interventions that increase muscle strength and power, whereas the effects of reducing between-limb asymmetry in these parameters might be of less importance.

Daily Protein and Energy Intake Are Not Associated with Muscle Mass and Physical Function in Healthy Older Individuals-A Cross-Sectional Study.

Dietary protein has a pivotal role in muscle mass maintenance with advancing age. However, an optimal dose and distribution of protein intake across the day as well as the interaction with energy intake for the maintenance of muscle mass and physical function in healthy older adults remain to be fully elucidated. The purpose of this study was to examine the association between muscle mass, strength, and physical function, and the total amount and distribution of protein and energy intake across the day in healthy older individuals. The research question was addressed in a cross-sectional study including 184 Danish men and woman (age: 70.2 ± 3.9 years, body mass: 74.9 ± 12.1 kg, Body Mass Index (BMI): 25.4 ± 3.7 kg/m2) where a 3-day dietary registration, muscle mass, strength, and functional measurements were collected. We found that neither daily total protein intake nor distribution throughout the day were associated with muscle mass, strength, or physical function. Consequently, we do not provide an incentive for healthy older Danish individuals who already adhere to the current internationally accepted recommended dietary protein intake (0.83 g/kg/day) to change dietary protein intake or its distribution pattern throughout the day.

Development of a Mobility Diet Score (MDS) and Associations With Bone Mineral Density and Muscle Function in Older Adults.

Introduction: Reduced bone mineral density (BMD) and muscle function is associated with increased risk of multiple health related issues. Diet may play a role in sustaining BMD and muscle function throughout old age, but much is still to be learned with regards to which specific food groups and dietary patterns that are important for such outcomes. The aim of the current study was to identify food groups important for both BMD and muscle function. Methods: A narrative review was performed on studies published on dietary patterns and their association with BMD and muscle function, respectively. Based on these findings, two dietary indices were constructed characterizing food groups associated with BMD and muscle function, respectively. Associations between adherence to these indices and BMD and muscle function were then investigated in a population of older community-dwelling Danes. Food groups found to be associated with both BMD and muscle function in our study population were suggested for inclusion into a common dietary index named the Mobility Diet Score. Results: In contrast to previous studies, adherence to a dietary index based on foods previously linked to BMD could not be established as important for BMD in our study population of 184 older individuals (53.3% men). We found that adhering to a dietary index characterized by higher intakes of whole grains, dairy products, fish, legumes, nuts, fruit, and vegetables is associated with faster 400 m walking speeds and an increased number of chair stands measured over a 30 s time period. Since no food group could be established as important for both BMD and muscle function in our study population, a Mobility Diet Score could not be established. However, based on our narrative review, the food groups commonly associated with improved BMD and muscle function are similar. Conclusion: Adherence to a dietary index characterized by high intakes of whole grains, dairy products, fish, legumes, nuts, fruit, and vegetables was not found to be associated with BMD in a group of community-dwelling older Danes. However, our results indicate that the adherence to such foods could be important in sustaining physical function in older individuals.