CrossTalk opposing view: Exercise training volume is more important than training intensity to promote increases in mitochondrial content

Rebuttal from Martin MacInnis, Lauren Skelly and Martin Gibala

“…), we contend that the pooled analysis from Bishop et al . () supports our position that training intensity is more important than training volume for increasing human skeletal muscle mitochondrial content.…”

“…As Bishop et al . () demonstrated that training volume was positively associated with changes in mitochondrial content, the similar increase in CS activity across training types, despite differences in training volume, is strong evidence that HIIT and SIT were more efficient than MICT for increasing mitochondrial content. Given the disparities across intervention types, the lack of correlation between exercise intensity and the change in mitochondrial content is unsurprising and is not evidence against the importance of exercise intensity.…”

“…We commend Bishop et al . () for their comprehensive summary but respectfully disagree with their conclusion that training volume is more important than exercise intensity for increasing mitochondrial content in human skeletal muscle. Their position, based on the compiled data, centres on: (1) a positive correlation between training volume and citrate synthase (CS) activity and mitochondrial volume density (Mito VD ); and (2) no correlation between training intensity and CS activity or Mito VD .…”

“…The analysis presented by Bishop et al . () is problematic for isolating the importance of exercise intensity per se . Firstly, on average, ∼37% more training sessions were performed for the moderate‐intensity continuous training (MICT) as compared to high‐intensity interval training (HIIT) and sprint interval training (SIT) (Granata et al .…”

Ingestion of Carbohydrate Prior to and during Maximal, Sprint Interval Cycling Has No Ergogenic Effect: A Randomized, Double-Blind, Placebo Controlled, Crossover Study

“…SIE is the performance of exercise at an 'all-out' or 'supramaximal' effort, separated by periods of active or passive recovery [7], and has been shown to be a potent stimulus to promote whole-body and skeletal muscle oxidative adaptations in both recreationally active and highly trained populations [8][9][10][11]. There is evidence to suggest that both exercise intensity and exercise volume are the two primary components in modulating increases in aerobic adaptations, such as mitochondrial content, through high intensity interval training [7,12]. Therefore, and firstly from a training perspective, there is the potential that the addition of exogenous CHO prior to or during sprint interval exercise may: allow an individual to exercise to exercise more intensely (rate of work done), or similarly, complete more work within a specified timeframe (i.e., greater volume of work completed).…”