Effect of resistance training and protein intake pattern on myofibrillar protein synthesis and proteome kinetics in older men in energy restriction

Abstract

We determined how the pattern of protein intake and resistance training (RT) influenced longer-term (2 weeks) integrated myofibrillar protein synthesis (MyoPS) during energy restriction (ER). MyoPS and proteome kinetics were measured during 2 weeks of ER alone and 2 weeks of ER plus RT (ER + RT) in overweight/obese older men. Participants were randomized to consume dietary protein in a balanced (BAL: 25% daily protein per meal × 4 meals) or skewed (SKEW: 7:17:72:4% daily protein per meal) pattern (n = 10 per group). Participants ingested deuterated water during the consecutive 2-week periods, and skeletal muscle biopsies and serum were obtained at the beginning and conclusion of ER and ER + RT. Bulk MyoPS (i.e. synthesis of the myofibrillar protein sub-fraction) and the synthetic rates of numerous individual skeletal muscle proteins were quantified. Bulk MyoPS was not affected by protein distribution during ER or ER + RT (ER: BAL = 1.24 ± 0.31%/day, SKEW = 1.26 ± 0.37%/day; ER + RT: BAL = 1.64 ± 0.48%/day, SKEW = 1.52 ± 0.66%/day) but was ∼26% higher during ER + RT than during ER (P = 0.023). The synthetic rates of 175 of 190 contractile, cytosolic and mitochondrial skeletal muscle proteins, as well as synthesis of muscle-derived proteins measured in serum, creatine kinase M-type (CK-M) and carbonic anhydrase 3 (CA-3), were higher during ER + RT than during ER (P < 0.05). In addition, the synthetic rates of CK-M and CA-3 measured in serum correlated with the synthetic rates of proteins obtained via muscle sampling (P < 0.05). This study provides novel data on the skeletal muscle adaptations to RT and dietary protein distribution.

Mitochondrial ATP synthase β‐subunit production rate and ATP synthase specific activity are reduced in skeletal muscle of humans with obesity

“…This observation is in line with findings in rodents, and where the synthesis rate of β‐F 1 ‐ATPase is closer to that of mixed‐muscle protein when compared to other mitochondrial proteins (Jaleel et al., ). The FSR of β‐F 1 ‐ATPase in our healthy sedentary lean humans (0.10 ± 0.05% h −1 ) was higher than that previously reported in either healthy sedentary (∼ 0.05% h −1 ) (Shankaran et al., ) or older overweight/obese (∼ 0.03% h −1 ) (Murphy et al., ) humans. In the latter studies, FSR of β‐F 1 ‐ATPase was measured using oral consumption of deuterated water.…”

“…In the latter studies, FSR of β‐F 1 ‐ATPase was measured using oral consumption of deuterated water. Although measurement of protein FSR using deuterated water compares well under certain circumstances with that using the traditional approach that is based on the incorporation of labelled amino acids into protein (Wilkinson et al., ), the deuterated water approach appeared previously to either overestimate (Murphy et al., ) or underestimate (Wilkinson et al., ) muscle protein FSR. There is still considerable debate with respect to the details describing the application of the deuterated water approach to accurately measure muscle protein FSR (Fluckey et al., ; Wilkinson, Atherton, Phillips, Greenhaff, & Smith, ).…”

The impact of exercise and nutrition on the regulation of skeletal muscle mass

“…How resistance exercise and nutrition affect turnover rates of the numerous individual proteins that constitute skeletal muscle has remained unknown until lately. In an attempt to address this knowledge gap, Murphy and colleagues () administered deuterated water (D 2 O) to their study participants and used tandem‐mass spectrometric proteomic analysis of muscle biopsy samples (Shankaran et al . ) to identify changes in the synthetic rates of > 150 individual muscle proteins contained in the myofibrillar, mitochondrial and sarcoplasmic protein fractions.…”

“…The primary finding from this study (Murphy et al . ) was that older adults performing resistance exercise during an energy restricted state enhanced the synthesis of 175 out of 195 measured individual skeletal muscle proteins in each of the specific protein fractions. Besides upregulation of individual skeletal muscle proteins in the myofibrillar (i.e.…”

The application of stable‐isotope tracers to study human musculoskeletal protein turnover: a tale of bag filling and bag enlargement

“…Clearly further validation of this approach is required, since the expected relationships are not always observed (Murphy et al . ) and there are limitations. One is that it would not allow the study of interventions in an individual limb or muscle.…”