Effects of Sprint versus High-Intensity Aerobic Interval Training on Cross-Country Mountain Biking Performance: A Randomized Controlled Trial

<div><p>Objectives</p><p>The current study compared the effects of high-intensity aerobic training (HIT) and sprint interval training (SIT) on mountain biking (MTB) race simulation performance and physiological variables, including peak power output (PPO), lactate threshold (LT) and onset of blood lactate accumulation (OBLA).</p><p>Methods</p><p>Sixteen mountain bikers (mean ± SD: age 32.1 ± 6.4 yr, body mass 69.2 ± 5.3 kg and VO_2max 63.4 ± 4.5 mL∙kg^-1∙min^-1) completed graded exercise and MTB performance tests before and after six weeks of training. The HIT (7–10 x [4–6 min—highest sustainable intensity / 4–6 min—CR100 10–15]) and SIT (8–12 x [30 s—all-out intensity / 4 min—CR100 10–15]) protocols were included in the participants’ regular training programs three times per week.</p><p>Results</p><p>Post-training analysis showed no significant differences between training modalities (HIT vs. SIT) in body mass, PPO, LT or OBLA (p = 0.30 to 0.94). The Cohen’s <i>d</i> effect size (ES) showed trivial to small effects on group factor (p = 0.00 to 0.56). The interaction between MTB race time and training modality was almost significant (p = 0.08), with a smaller ES in HIT vs. SIT training (ES = -0.43). A time main effect (pre- vs. post-phases) was observed in MTB race performance and in several physiological variables (p = 0.001 to 0.046). Co-variance analysis revealed that the HIT (p = 0.043) group had significantly better MTB race performance measures than the SIT group. Furthermore, magnitude-based inferences showed HIT to be of likely greater benefit (83.5%) with a lower probability of harmful effects (0.8%) compared to SIT.</p><p>Conclusion</p><p>The results of the current study suggest that six weeks of either HIT or SIT may be effective at increasing MTB race performance; however, HIT may be a preferable strategy.</p><p>Trial Registration</p><p>ClinicalTrials.gov <a href="https://clinicaltrials.gov/ct2/show/NCT01944865" target="_blank">NCT01944865</a></p></div

Computer-simulated course showing the (A) overall and (B) specific distance and gradient profile used in this study.

<p>Computer-simulated course showing the (A) overall and (B) specific distance and gradient profile used in this study.</p

Simulation performance before (PRE) and after (POST) 6 weeks of HIT or SIT.

<p>*p<0.001 versus pre-training (main effect for time). Lines denote individual data for 7 subjects in the HIT group and 9 subjects in the SIT group. HIT—high-intensity aerobic interval training; SIT—sprint interval training.</p

Average weekly training loads of HIT and SIT groups.

<p>Calculated using the session rating of perceived exertion (RPE) method, i.e., multiplying the cyclist RPE (using the Category Ratio Scale; CR100) referring to the whole training session by session duration in minutes. HIT—high-intensity aerobic interval training; SIT—sprint interval training; a.u.—arbitrary units.</p

Forrest plot of percentage changes (ANCOVA) with 95% confidence intervals between HIT and SIT.

<p>The vertical zero-line represents SIT. BM—body mass; PPO—peak power output; LT—lactate threshold; OBLA—onset of blood lactate accumulation; HIT—high-intensity aerobic interval training; SIT—sprint interval training; Δ %—percentage change.</p

A cartoon representation demonstrates an overview of the absolute beta power results in different areas of frontal cortex.

<p>The arrow “<b>↑</b>” means an increase of absolute beta power. The arrow “<b>↓</b>” means a decrease of absolute beta power and the double arrow “<b>↔</b>” means no modification in absolute beta power.</p

Absolute beta power of inferior prefrontal gyrus.

<p>Values are expressed as means and standard error. * Significant difference (p ≤ 0.05). This figure shows the absolute beta power of inferior prefrontal gyrus (F7 e F8), in each treatment (Placebo, Taurine, Ethanol and Taurine + Ethanol) before (baseline and peak) and after (post-exercise) exercise.</p

Absolute beta power of anterior prefrontal.

<p>Values are expressed as means and standard error. * Significant difference (p ≤ 0.05). This figure shows the absolute beta power of anterior prefrontal area (Fp1 e Fp2), in each treatment (Placebo, Taurine, Ethanol and Taurine + Ethanol) before (baseline and peak) and after (post-exercise) exercise.</p

Plasma ethanol concentrations.

<p>Plasma ethanol concentrations.</p

Absolute beta power of superior frontal gyrus.

<p>Values are expressed as means and standard error. * Significant difference (p ≤ 0.05). This figure shows the absolute beta power of superior prefrontal gyrus (F3, F4 e Fz), in each treatment (Placebo, Taurine, Ethanol and Taurine + Ethanol), before (baseline and peak) and after (post-exercise) exercise.</p