Hypoenergetic diet-induced reductions in myofibrillar protein synthesis are restored with resistance training and balanced daily protein ingestion in older men.
Strategies to enhance weight loss with a high fat-to-lean ratio in overweight/obese older adults are important since lean loss could exacerbate sarcopenia. We examined how dietary protein distribution affected muscle protein synthesis during energy balance (EB), energy restriction (ER), and energy restriction plus resistance training (ER + RT). A 4-wk ER diet was provided to overweight/obese older men (66 ± 4 yr, 31 ± 5 kg/m(2)) who were randomized to either a balanced (BAL: 25% daily protein/meal × 4) or skewed (SKEW: 7:17:72:4% daily protein/meal; n = 10/group) pattern. Myofibrillar and sarcoplasmic protein fractional synthetic rates (FSR) were measured during a 13-h primed continuous infusion of l-[ring-(13)C6]phenylalanine with BAL and SKEW pattern of protein intake in EB, after 2 wk ER, and after 2 wk ER + RT. Fed-state myofibrillar FSR was lower in ER than EB in both groups (P < 0.001), but was greater in BAL than SKEW (P = 0.014). In ER + RT, fed-state myofibrillar FSR increased above ER in both groups and in BAL was not different from EB (P = 0.903). In SKEW myofibrillar FSR remained lower than EB (P = 0.002) and lower than BAL (P = 0.006). Fed-state sarcoplasmic protein FSR was reduced similarly in ER and ER + RT compared with EB (P < 0.01) in both groups. During ER in overweight/obese older men a BAL consumption of protein stimulated the synthesis of muscle contractile proteins more effectively than traditional, SKEW distribution. Combining RT with a BAL protein distribution "rescued" the lower rates of myofibrillar protein synthesis during moderate ER.
Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada;
Caoileann H
CH
Murphy
Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada;
Tyler A
TA
Churchward-Venne
Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada;
Cameron J
CJ
Mitchell
Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada;
Nathan M
NM
Kolar
Nestlé Research Center, Nestec, Lausanne, Switzerland.
Amira
A
Kassis
Nestlé Research Center, Nestec, Lausanne, Switzerland.
Leonidas G
LG
Karagounis
Department of Sports Nutrition, Australian Institute of Sport, Canberra, Australia;
Louise M
LM
Burke
Exercise and Nutrition Research Group, School of Exercise Science, Australian Catholic University, Fitzroy, Victoria, Australia; Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, United Kingdom; and.
John A
JA
Hawley
Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada; phillis@mcmaster.ca.
Stuart M
SM
Phillips
D000368:Aged; D000375:Aging / Q000378:metabolism; D001823:Body Composition / Q000187:drug effects; D031204:Caloric Restriction / Q000009:adverse effects*; D004038:Diet, Reducing / Q000009:adverse effects; D004044:Dietary Proteins / Q000494:pharmacology*; D004435:Eating; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000187:drug effects; D009133:Muscular Atrophy / Q000209:etiology / Q000378:metabolism / Q000534:rehabilitation; D014176:Protein Biosynthesis / Q000187:drug effects; D055070:Resistance Training
D004044:Dietary Proteins; D009124:Muscle Proteins
aging; energy restriction; stable isotope