Moderate Increase in Protein Intake Promotes a Small Additional Improvement in Functional Capacity, But Not in Muscle Strength and Lean Mass Quality, in Postmenopausal Women Following Resistance Exercise: A Randomized Clinical Trial.

Paula C Nahas,Fábio L Orsatti,Marcelo A S Carneiro,Erick P De Oliveira,Flávia M S De Branco,Fernanda M Martins,Luana T Rossato,Aletéia P Souza,Kely R C Teixeira

doi:10.3390/nu11061323

Paula C Nahas, Fábio L Orsatti + Show 7 more

Open Access

https://doi.org/10.3390/nu11061323

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Abstract

The aim of this study was to evaluate the effect of a moderate increase in protein intake on muscle strength, functional capacity and lean mass quality improvements in postmenopausal women following resistance exercise. Forty-seven postmenopausal women were randomized in two groups: Normal protein (NP, n = 25), who received a dietary plan containing ~0.8 g protein·kg−1·d−1 (recommended dietary allowance—RDA recommendations); and higher protein (HP, n = 22), which a moderate increase in protein intake was recommended (~1.2 g protein·kg−1·d−1). Resistance training was performed for 10 weeks, three times/week. Muscle strength (handgrip strength and one repetition maximum test—1-RM), functional capacity and lean mass (LM) quality (muscle strength to lean mass ratio) were evaluated. Dietary intake was assessed by nine 24 h food recalls. After intervention, both groups increased similarly the leg extension 1-RM and handgrip strength. Regarding functional capacity tests, both groups increased the balance test score (SPPB) and 10 m walk test speed, with no differences between the groups. In addition, an increase in speed to perform the 6 min and 400 m walk tests was observed over the time, with an additional improvement in the HP group (time × group interaction; p = 0.007 and p = 0.004, respectively). About LM quality, leg extension 1-RM/leg LM improved over the time in both groups (p = 0.050), with no time × group interaction. All these significant changes had a low effect size. In conclusion, a moderate increase in protein intake promoted a small additional improvement in functional capacity, but it did not induce a greater increase in strength and LM quality after 10 weeks of resistance exercise in postmenopausal women. This trial was registered at ClinicalTrials.gov as NCT03024125.

Highlights

Aging promotes a progressive and generalized loss of lean mass (LM), muscle function and strength [1] mainly due to “anabolic resistance” [2,3], which can be aggravated by a combination of several factors, such as a sedentary lifestyle [4] and low protein intake [3,5]
We hypothesized that a moderate increase in protein intake would promote additional strength, functional capacity and LM quality improvements induced by resistance exercise protocol
No differences were observed between groups for age, energy expenditure, anthropometric measurements, body composition, strength, functional capacity and LM quality at baseline (Table 1)

Summary

Introduction

Aging promotes a progressive and generalized loss of lean mass (LM), muscle function and strength [1] mainly due to “anabolic resistance” [2,3], which can be aggravated by a combination of several factors, such as a sedentary lifestyle [4] and low protein intake [3,5]. Postmenopausal period results in ovarian follicular activity loss and a reduction in estrogen production in women [6], which may promote additional effects on LM, strength and functional losses [7,8]. In addition to strength and functional capacity evaluation, LM quality (strength to LM ratio [11]) is another important parameter to be evaluated in this population, since it is a predictor of the risk of mobility limitation [12,13]. LM quality can be a complementary assessment to evaluate strength gains independently of muscle hypertrophy [1] In this way, strength, functional capacity and LM quality are important parameters to be evaluated and interventions aiming to improve muscle function can increase the quality of life in older women [1,14]

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