HIT Training: Performance Outcomes and Factors Affecting Repeat Sprint Ability

Performance Outcomes with HIT Training

Examined the effects of two weeks of sprint interval training on oxidative potential and cycle endurance capacity.
Intervention:
- Six sessions over two weeks of sprint interval training.
- 30-second bouts.
- Control group.
Performance Test:
- Endurance capacity: time to failure at 80% of VO_2 max.
Results:
- 38% increase in citrate synthase activity.
- 100% improvement in cycle performance after only two weeks.
- Significant improvements in time to failure performance with sprint interval training.

Examined the effects of low volume sprint training and high volume endurance training.
Interventions: Six training sessions over fourteen days.
- Sprint Interval Training (SIT): 2.5-hour training commitment.
- Endurance Training (ET): 10.5-hour training commitment (4x the SIT time).
Results:
- 10.1% reduction in time to complete a 750 kilojoule cycling test in the SIT group.
- 7.5% improvement in the ET group.
- Significant improvement in muscle oxidative capacity, equal between groups.
- Same with muscle buffering capacity.
Sprint interval training can yield similar or better improvements compared to high volume endurance training in less time.
Larsen and Jenkins review findings:
- Summary of findings in high intensity interval training studies in highly trained cyclists.
  - Improvements in time to fatigue, time trial performance, etc.
- Results for high intensity interval training in trained runners.
  - Decreases in 10-kilometer time.
  - Reductions in RER ratio indicating better fat metabolism.
  - Decreases in 3-kilometer time, velocity max, etc.
- Table 2 shows changes in cycle repeated sprintability following different types of training on a cycle ergometer.
  - Improvements in sprint total work.
  - Improvements in VO_2 max (up to 14.6%).

Muscle fibre type distribution and activity of creatine kinase before and after speed training intervention and speed endurance training.
8-week duration program with varying training frequency across the weeks.
Training Programs:
- Speed Training (ST): 15 six-second runs with 1-min recovery at 95% max speed.
- Speed Endurance Training (SET): 8 thirty-second runs with 1.5-min recovery between each; intensity ~130% VO_2 max.
Heart rate responses were greater for speed endurance training.
Physiological Adaptations (Table 3):
- Changes in muscle protein, phosphate, lactate, pH, and glycogen rest and exhaustion, and three minutes after the Yo-Yo Intermittent Recovery Test before and after each training program.
- High amounts of lactate production for the speed endurance training.
- Differences between groups in terms of muscle glycogen and pH.
Performance Outcomes:
- Greater improvements for the SAT group in Yo-Yo test performance and treadmill test performance.
- Reductions in 30-minute mean and peak times.
- Improved fatigue index.
- The SAT format might be better than the pure speed training format.

Analysis of pre-training and post-training individual and mean sprint times from a repeated sprint test consisting of five 30-meter sprints with 25-second rest periods.
ST group: intermediate sprint training.
SET group: speed endurance training.
Significant decrease in initial sprint time only for the ST group.
Significant decrease in mean sprint time for both groups.
Repeated sprintability improved with both training formats.

High intensity training (HIT): two-minute intervals with one-minute recovery.
- Intensity determined by individual lactate threshold.
Moderate intensity continuous training (MIT): Trained at an intensity based upon the individual lactate threshold.
- Progression controlled by increasing duration.
Improvements in total work and peak power for both groups, but greater for the HIT group.
Total work performed post-training compared to pre-training was greater for the high intensity training group compared to the moderate intensity continuous training group.

Effect of varying the intensity of interval training on changes in 40 kilometer cycling time trial performance (well-trained cyclists).
Five groups with different doses of high intensity interval training:
- 12 x 30-second efforts at 175% of peak sustained power output.
- 12 x 1-minute at 100% of peak power output.
- 12 x 2-minute at 9% of peak power output.
- 8 x 4-minute at 85% of peak power output.
- 4 x 8-minute at 80% of peak power output.
Six sessions over a three-week period, in addition to their usual training.
Improvements in 40-kilometer time trial speed for two groups:
- 12 x 1-minute at 100% of peak power output.
- 8 x 4-minute at 85% of peak power output.
- Improvements of approximately 2-4%.