Protein-enriched diet, with the use of lean red meat, combined with progressive resistance training enhances lean tissue mass and muscle strength and reduces circulating IL-6 concentrations in elderly women: a cluster randomized controlled trial

doi:10.3945/ajcn.113.064154

The American Journal of Clinical Nutrition

Volume 99, Issue 4, April 2014, Pages 899-910

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ABSTRACT

Background:

Physical inactivity, inadequate dietary protein, and low-grade systemic inflammation contribute to age-related muscle loss, impaired function, and disability.

Objective:

We assessed the effects of progressive resistance training (PRT) combined with a protein-enriched diet facilitated through lean red meat on lean tissue mass (LTM), muscle size, strength and function, circulating inflammatory markers, blood pressure, and lipids in elderly women.

Design:

In a 4-mo cluster randomized controlled trial, 100 women aged 60–90 y who were residing in 15 retirement villages were allocated to receive PRT with lean red meat (∼160 g cooked) to be consumed 6 d/wk [resistance training plus lean red meat (RT+Meat) group; n = 53] or control PRT [1 serving pasta or rice/d; control resistance training (CRT) group; n = 47)]. All women undertook PRT 2 times/wk and received 1000 IU vitamin D₃/d.

Results:

The mean (± SD) protein intake was greater in the RT+Meat group than in the CRT group throughout the study (1.3 ± 0.3 compared with 1.1 ± 0.3 g · kg⁻¹ · d⁻¹, respectively; P < 0.05). The RT+Meat group experienced greater gains in total body LTM (0.45 kg; 95% CI: 0.07, 0.84 kg), leg LTM (0.22 kg; 95% CI: 0.02, 0.42 kg), and muscle strength (18%; 95% CI: 0.03, 0.34) than did the CRT group (all P < 0.05). The RT+Meat group also experienced a 10% greater increase in serum insulin-like growth factor I (P < 0.05) and a 16% greater reduction in the proinflammatory marker interleukin-6 (IL-6) (P < 0.05) after 4 mo. There were no between-group differences for the change in blood lipids or blood pressure.

Conclusion:

A protein-enriched diet equivalent to ∼1.3 g · kg⁻¹ · d⁻¹ achieved through lean red meat is safe and effective for enhancing the effects of PRT on LTM and muscle strength and reducing circulating IL-6 concentrations in elderly women. This trial was registered at the Australian Clinical Trials Registry as ACTRN12609000223235.

Cited by (0)

^¹: From the Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Australia (RMD, SLO, NLM, CAG, DWD, and CAN), and the Baker IDI Heart and Diabetes Institute, Melbourne, Australia (DWD).

^²: The sponsor had no role in the design and conduct of the study; collection, management, and interpretation of the data; or preparation of the manuscript.

^³: Supported by a competitive, peer-reviewed grant from Meat and Livestock Australia Ltd, a National Health and Medical Research Council Career Development Award (ID 425849; to RMD), and an Australian Research Council Future Fellowship (FT 100100918; to DWD).

^⁴: Address reprint requests and correspondence to RM Daly, Centre for Physical Activity and Nutrition Research, Deakin University, 221 Burwood Highway, Burwood, Victoria 3125, Australia. E-mail: [email protected].

^⁵: Abbreviations used: BMD, bone mineral density; CRT, control resistance training; CSA, cross-sectional area; DXA, dual-energy X-ray absorptiometry; eGFR, estimated glomerular filtration rate; FM, fat mass; FSST, 4-square step test; IGF-I, insulin-like growth factor I; LTM, lean tissue mass; MPB, muscle protein breakdown; MPS, muscle protein synthesis; PRT, progressive resistance training; RM, repetition maximum; RT+Meat, resistance training plus lean red meat; STS, sit-to-stand test; TUG, timed-up-and-go test.