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Suga H, Hashimoto H. Age threshold for recommending higher protein intake to prevent age-related muscle weakness: A cross-sectional study in Japan. PLoS One 2018; 13:e0208169. [PMID: 30540812 PMCID: PMC6291077 DOI: 10.1371/journal.pone.0208169] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 11/13/2018] [Indexed: 12/17/2022] Open
Abstract
Although insufficient dietary protein intake is a known risk factor for age-related muscle weakness, the optimal age at which higher protein intake is required to prevent muscle weakness is yet to be determined. Using a population-based panel survey of community-dwelling people aged 50-75 years, this cross-sectional study aimed to find the age threshold at which a higher protein intake is associated with higher muscle strength. We utilized a dataset from the Japanese Study of Aging and Retirement conducted between 2007 and 2011. Dietary protein intake was estimated using a validated dietary questionnaire and energy-adjusted via density method. Grip strength was measured using a Smedley-type handheld dynamometer. We calculated the marginal effect (and 95% confidence intervals) of protein intake on grip strength with stratification by age using multiple linear regression analyses with robust variance adjusting for potential confounders. There were 9,485 observations from 5,790 participants in the final analysis. Marginal effects of protein intake on grip strength increased with age, and it reached significance and had a positive impact only among men aged ≥75 years and women aged ≥65 years. With an additional 1% energy of protein intake, grip strength was increased by 0.10 kg and 0.19 kg for men and women aged ≥75 years, respectively. Our result indicated the possibility that women needed a high protein intake from a younger age compared with men. Further studies are needed to clarify from when a higher protein intake is recommended to prevent muscle weakness.
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Affiliation(s)
- Hitomi Suga
- Department of Social and Preventive Epidemiology, School of Public Health, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Hideki Hashimoto
- Departments of Health and Social Behavior, School of Public Health, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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Hirsch KR, Tweedell AJ, Kleinberg CR, Gerstner GR, Barnette T, Mota JA, Smith-Ryan AE, Ryan ED. The Influence of Habitual Protein Intake on Body Composition and Muscular Strength in Career Firefighters. J Am Coll Nutr 2018; 37:620-626. [PMID: 29702029 PMCID: PMC6192035 DOI: 10.1080/07315724.2018.1455071] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 03/17/2018] [Indexed: 02/09/2023]
Abstract
OBJECTIVE The aim of this research was to determine the relationship among protein (PRO) intake, body composition, and muscle strength in overweight and obese firefighters. A secondary objective was to evaluate differences in body composition and muscle strength among overweight and obese firefighters with low (L; < 0.8 g·kg-1), moderate (M; 0.8-1.0 g·kg-1), and high (H; > 1.0 g·kg-1) PRO intake. METHODS Relative PRO intake [r_PRO] was evaluated from 3-day dietary logs, self-reported by 43 overweight and obese male career firefighters (mean ± standard deviation; age = 37.3 ± 7.2 years; body mass index = 33.2 ± 5.0 kg·m-2; percent body fat [%BF] = 28.9 ± 4.0%). Body composition (fat mass [FM], %BF, lean mass [LM], percent LM [%LM]) and muscle strength (peak torque [PT], relative peak torque [r_PT] of the leg extensors) were measured using dual-energy x-ray absorptiometry and isokinetic dynamometry, respectively. RESULTS Greater r_PRO was associated with less FM, %BF, LM (r = -0.498 to -0.363) and greater %LM (r = 0.363), but not muscle strength (p > 0.05). Fat mass (r = -0.373) and %BF (r = -0.369) were associated with lower r_PT; %LM was associated with greater r_PT (r = 0.373). Individuals with L r_PRO had greater FM (mean difference ± standard error: L-H = 10.08 ± 3.18 kg), %BF (L-H = 3.8% ± 1.4%) and lower %LM (L-H = -3.7% ± 1.3%) than those with H r_PRO (p < 0.05) but no significant differences in muscle strength (p > 0.05). CONCLUSIONS Protein intake > 0.8 g·kg-1 was associated with more favorable body composition in male career firefighters.
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Affiliation(s)
- Katie R. Hirsch
- Applied Physiology Laboratory, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, NC, USA
- Human Movement Science Curriculum, Department of Allied Health Science, University of North Carolina Chapel Hill, NC, USA
| | - Andrew J. Tweedell
- Neuromuscular Research Laboratory, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, NC, USA
| | - Craig R. Kleinberg
- Neuromuscular Research Laboratory, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, NC, USA
| | - Gena R. Gerstner
- Human Movement Science Curriculum, Department of Allied Health Science, University of North Carolina Chapel Hill, NC, USA
- Neuromuscular Research Laboratory, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, NC, USA
| | - T.J. Barnette
- Neuromuscular Research Laboratory, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, NC, USA
| | - Jacob A. Mota
- Human Movement Science Curriculum, Department of Allied Health Science, University of North Carolina Chapel Hill, NC, USA
- Neuromuscular Research Laboratory, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, NC, USA
| | - Abbie E. Smith-Ryan
- Applied Physiology Laboratory, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, NC, USA
- Human Movement Science Curriculum, Department of Allied Health Science, University of North Carolina Chapel Hill, NC, USA
| | - Eric D. Ryan
- Human Movement Science Curriculum, Department of Allied Health Science, University of North Carolina Chapel Hill, NC, USA
- Neuromuscular Research Laboratory, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, NC, USA
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Influence of Manual Labor at Work on Muscular Fitness and Its Relationship With Work Performance. J Occup Environ Med 2018; 58:1034-1039. [PMID: 27753748 DOI: 10.1097/jom.0000000000000860] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The present study examined the influence of workplace manual labor on measures of muscular fitness, with a secondary aim to investigate the relationship between muscular fitness and work performance in blue-collar (BC) workers. METHODS Leg extension isokinetic strength at slow and fast velocities, hamstring and hip-flexor flexibility, and low back muscular endurance were examined in young and older BC workers and white-collar (WC) controls, while work performance was examined in the BC cohort. RESULTS There were no differences in muscular fitness variables between BC and WC groups; however, the older men had lower low back muscular endurance (-43.0%) and strength at slow (-9.4%) and fast (-12.7%) velocities. Work performance was associated with strength at fast velocities (r = 0.633) in the older BC workers. CONCLUSIONS Leg strength may influence work performance, with higher velocities becoming more important in older workers.
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