Transient transcriptional events in human skeletal muscle at the outset of concentric resistance exercise training

Abstract

We sought to ascertain the time course of transcriptional events that occur in human skeletal muscle at the outset of resistance exercise (RE) training in RE naive individuals and determine whether the magnitude of response was associated with exercise-induced muscle damage. Sixteen RE naive men were recruited; eight underwent two sessions of 5 × 30 maximum isokinetic knee extensions (180°/s) separated by 48 h. Muscle biopsies of the vastus lateralis, obtained from different sites, were taken at baseline and 24 h after each exercise bout. Eight individuals acted as nonexercise controls with biopsies obtained at the same time intervals. Transcriptional changes were assessed by microarray and protein levels of heat shock protein (HSP) 27 and αB-crystallin in muscle cross sections by immunohistochemistry as a proxy measure of muscle damage. In control subjects, no probe sets were significantly altered (false discovery rate < 0.05), and HSP27 and αB-crystallin protein remained unchanged throughout the study. In exercised subjects, significant intersubject variability following the initial RE bout was observed in the muscle transcriptome, with greatest changes occurring in subjects with elevated HSP27 and αB-crystallin protein. Following the second bout, the transcriptome response was more consistent, revealing a cohort of probe sets associated with immune activation, the suppression of oxidative metabolism, and ubiquitination, as differentially regulated. The results reveal that the initial transcriptional response to RE is variable in RE naive volunteers, potentially associated with muscle damage and unlikely to reflect longer term adaptations to RE training. These results highlight the importance of considering multiple time points when determining the transcriptional response to RE and associated physiological adaptation.

Synchronous deficits in cumulative muscle protein synthesis and ribosomal biogenesis underlie age‐related anabolic resistance to exercise in humans

“…However, early transcriptional responses are quickly modifiable (Murton et al . ) and activation of key signalling proteins is attenuated with repeated exercise stimulus (Ogasawara et al . ).…”

Effects of exercise with and without different degrees of blood flow restriction on torque and muscle activation

“…Physically active participants were used to reflect better the actual acute responses to different exercises. The use of this population decreases the chance of erroneously quantifying acute changes more reflective of muscle damage from an unaccustomed bout of exercise . In addition, different subjects were used in the 3 separate experiments to lessen the chance of producing and quantifying a training effect.…”

Leucine supplementation enhances integrative myofibrillar protein synthesis in free-living older men consuming lower- and higher-protein diets: a parallel-group crossover study

“…On day 3, participants performed an identical REX session with the exception that the exercise was performed on the right leg and that repetitions were clamped at the same number of repetitions per set that were achieved on day 0. The exercise was performed on different legs in the placebo and Leu treatments in view of previous work that suggested that the acute transcriptional (27) and protein synthetic (28) responses to an initial bout of REX may vary substantially from the responses to subsequent bouts in untrained individuals. Therefore, varying the exercise leg allowed us to examine the MyoPS response to REX in an exercise-naive leg during both the placebo and Leu treatments.…”