Effects of a gluten-free diet combined with sprint interval training on feasibility, performance and health outcomes in non-professional endurance athletes: a pilot trial
Question
Is a gluten-free diet combined with standardized sprint interval training feasible, and does it affect performance or health outcomes compared with a mixed diet in non-professional endurance athletes?
Summary
In healthy male non-professional endurance athletes, a 6-week gluten-free diet combined with supervised sprint interval training was feasible for completers but had lower retention than a mixed-diet comparison. Performance outcomes did not show a clear gluten-free advantage. The sprint protocol is useful background, but the main evidence is about diet feasibility, not HIIT programming.
Methodology
- Healthy male non-professional endurance athletes aged 18-50 years.
- 20 participants.
- Diet intervention plus supervised cycle sprint interval training.
- Work intervals: 30 seconds.
- Recovery: 4 minutes.
- Intensity: All-out Wingate-style sprints; warm-up/recovery/cooldown at 70-80% HRmax below ventilatory threshold.
- Warm-up, 4-6 sprint/recovery repetitions, and cooldown.
- 3 sessions per week.
- 6 weeks; 18 sessions.
- Monocentric prospective open-label matched-group pilot trial
- Feasibility, Performance, Body composition and blood pressure, and GI and nutrition were tracked.
Outcomes
Retention
Retention was lower in the gluten-free diet group than the mixed-diet group.
Final analysis: GFD 6/10 retained (60%) and MD 9/10 retained (90%); 15 of 20 enrolled completed.
Training adherence
Completers attended nearly all sprint sessions in both groups.
Training sessions completed 17 +/- 1 in both groups, p=0.529; key outcome completeness 100%; no major protocol deviations.
Performance
The gluten-free diet did not show a clear performance advantage over mixed diet.
The article reports no clear significant between-group advantage for performance outcomes such as VO2peak, thresholds, substrate oxidation, time to exhaustion, or time trial.
Body mass
Weight and BMI changes differed between groups favoring gluten-free diet, but other body-composition and BP outcomes did not clearly differ.
Between-group differences for weight and BMI changes p=0.018 and p=0.026; no significant between-group differences for fat mass, fat-free mass, or blood pressure.
Insights
- A 6-week progressive 30-second Wingate-style SIT protocol was completed with high attendance among athlete completers.
- A gluten-free diet should not be presented as improving endurance performance in non-celiac athletes based on this pilot.
- Diet interventions can reduce retention even when training adherence among completers is high.
Limitations
- Small pilot sample with only 15 analyzed completers.
- Non-randomized open-label matched-group design.
- Male endurance athletes only.
- Lower retention in the gluten-free group.
- Self-reported diet and no mechanistic biomarkers.
- Outdoor performance testing was vulnerable to environmental variability.
- No non-training control group.
Safety
- No adverse events or pathological findings were reported via anamnesis/compliance calendar.
- Dropouts were voluntary withdrawals because participants did not continue dietary/training participation.
- Participants were screened for celiac disease, special diets, and contraindications to physical activity.