Research

Energy balance

High-intensity interval training improves endurance performance by shifting fuel utilization towards fat oxidation and reducing carbohydrate reliance at submaximal absolute work rates, thereby delaying lactate accumulation and muscle acidosis.

To get faster, focus on training that forces your body to burn fat more efficiently at high speeds and improves your muscles' ability to handle acid buildup. This allows you to sustain higher speeds for longer without 'hitting the wall' or slowing down due to fatigue. This is achieved through high-intensity intervals, not just long, slow rides.

GoodSupportsHIGH confidence
Part of the explanation for the finding that the cyclists were able to sustain higher work rates in the 40 km time-trial rides after the HIT programme may have been a decreased reliance on carbohydrate as a fuel source... Lower venous plasma lactate concentrations at the same absolute - but not at the same relative - exercise intensities after high-intensity interval training were associated with the reduced reliance on carbohydrate oxidation at those work rates.
John A. Hawley et al. · Journal of Sports Sciences · 1997

Why this rating

Supported by muscle biopsy data and metabolic measurements in the same cohort as N1.

Source

Training techniques to improve fatigue resistance and enhance endurance performance

John A. Hawley et al. · Journal of Sports Sciences · 1997

DOI 10.1080/026404197367335

narrative_review · n=20Cited 152×
Read the paper
DOI resolved against Crossref · corpus check 2026-06-10

This is one finding among thousands. Every one is graded and traced to its source, so you can see what the evidence actually supports. Browse the research →