Effects of an increased habitual dietary protein intake followed by resistance training on fitness, muscle quality and body composition of seniors: A randomised controlled trial.
Study Goal
The researchers aimed to determine if doubling the recommended protein intake (1 g/kg BW/d) in older adults is achievable through food and whether this higher intake, combined with resistance training, leads to greater improvements in muscle mass, strength, and function.
Results Summary
The study found that increasing protein intake above recommended levels was achievable, but the higher intake led to only minor changes in body composition (reduced fat mass and increased muscle mass in the high-protein group) without significant improvements in physical performance or muscle quality. Most physical performance parameters improved over time, but no group-specific benefits were observed.
Population
Community-dwelling older adults (54% female, average age 72.9 ± 4.8 years).
Effective Dosage
Recommended protein (RP + T): ~1 g/kg BW/d; High protein (HP + T): ~2 g/kg BW/d.
Duration
17 weeks (6 weeks of nutritional counseling, followed by 8 weeks of resistance training).
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
nutritional counselling to achieve recommended protein target levels | increase | protein intake | community-dwelling older adults in RP + T group | 0.18 ± 0.31 g/kg BW/d | increased | #1 |
nutritional counselling to achieve high protein target levels | increase | protein intake | community-dwelling older adults in HP + T group | 0.83 ± 0.33 g/kg BW/d | increased | #2 |
observation | no change | protein intake | community-dwelling older adults in CON group | - | remained unchanged | #3 |
resistance training combined with nutritional counselling | increase | most physical performance parameters | community-dwelling older adults | - | improved | #4 |
nutritional counselling | increase | body fat mass | community-dwelling older adults | 0.8 ± 2.3 kg | increased | #5 |
nutritional counselling | decrease | skeletal muscle mass | community-dwelling older adults | -0.5 ± 1.9 kg | decreased | #6 |
resistance training combined with high protein intake | decrease | body fat mass | community-dwelling older adults in HP + T group | -0.47 ± 2.12 kg | decreased | #7 |
resistance training combined with high protein intake | increase | muscle mass | community-dwelling older adults in HP + T group | 0.51 ± 1.57 kg | increased | #8 |
extra amount of protein | increase | body composition | community-dwelling older adults | - | led to minor changes | #9 |
extra amount of protein | no change | physical performance | community-dwelling older adults | - | did not lead to changes | #10 |
extra amount of protein | no change | muscle quality | community-dwelling older adults | - | did not lead to changes | #11 |
BACKGROUND & AIMS: Resistance training and a sufficient amount of dietary protein have been suggested to build up and maintain muscle mass, strength and function into old age. As there is still no consensus on the optimum amount of protein intake in older people, this study aims to evaluate first whether it is achievable to double the recommended amount, which is 1 g/kg BW/d in German speaking countries, via food administration and secondly whether this would lead to stronger improvements when subsequently combined with resistance training. METHODS: In total, 136 community-dwelling older adults (54% females, 72.9 ± 4.8 yrs) were randomly assigned to one of the three study groups: observational control (CON), recommended protein (RP + T) and high protein (HP + T) intake groups. After six weeks of observation or nutritional counselling to achieve the respective protein target levels, eight weeks of resistance training (2x/week) were applied in RP + T and HP + T groups. Parameters indicative for muscle mass, strength and function were measured at baseline (t1), before (t2) and after the training period (t3). RESULTS: Baseline protein intake for the different groups were 0.83 (CON), 0.97 (RP + T) and 0.78 (HP + T) g/kg BW/d and increased by 0.18 ± 0.31 (RP + T, p = 0.003) and 0.83 ± 0.33 (HP + T, p > 0.001) g/kg BW/d between t1 and t3 while CON remained unchanged. Most of the physical performance parameters improved over time, but no interaction effects between group and time could be observed. While body fat mass initially increased from t1 to t2 (0.8 ± 2.3 kg, p = 0.001), skeletal muscle mass decreased (-0.5 ± 1.9 kg, p = 0.025), a trend which was reversed from t2 to t3 only in HP + T group (body fat mass: -0.47 ± 2.12 kg, p = 0.041; muscle mass: 0.51 ± 1.57 kg, p = 0.021). CONCLUSION: The findings suggest that a substantial increase of habitual protein intake above the currently recommended levels is achievable within 17 weeks in community-dwelling older adults, whereby the extra amount of protein led to minor changes in body composition but not physical performance or muscle quality (NCT04023513).