Effects of acute and chronic exercise on sarcolemmal MCT1 and MCT4 contents in human skeletal muscles: current status.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing existing human studies without systematic search methodology
PubMed 22012699 · doi:10.1152/ajpregu.00250.2011
What was done
Narrative review synthesizing evidence on the effects of acute exercise, chronic training, and related metabolic stimuli (hypoxia, nutrition) on skeletal muscle sarcolemmal monocarboxylate transporters (MCT1 and MCT4) and lactate transport capacity in humans.
What was found
No quantitative effect sizes or numerical values are reported in the abstract. Acute exercise alters MCT content within 24 hours, with discordance between mRNA and protein levels. Exercise generally produces greater increases in MCT1 than in MCT4 content. Chronic training alters both isoforms regardless of baseline fitness, with cross-sectional studies identifying exercise intensity as the primary driver. Changes in MCT protein content frequently dissociate from functional lactate transport activity.
Why it matters
Clarifies how muscle pH and lactate transport mechanisms adapt to exercise, highlighting that protein expression alone does not fully predict functional transport capacity.
Limits
As a narrative review, it lacks systematic search criteria, quality appraisal, and meta-analytic pooling. The abstract reports no numerical data, relies on cross-sectional studies for key intensity conclusions, and notes a dissociation between transporter abundance and functional transport.
Cited by
- supports High-intensity exercise training leads to an upregulation of monocarboxylate transporters (MCTs) in skeletal muscle to facilitate lactate transport.