BLUF (Bottom Line Up Front)
This study compared High-Intensity Functional Training (HIFT) with Traditional Military Physical Training (TMPT) over a 19-week period in conscripts. HIFT proved to be a more effective and time-efficient approach for improving aerobic endurance and strength, despite incorporating less total running volume than TMPT. HIFT resulted in greater improvements in aerobic capacity, upper- and lower-body strength, and power, while TMPT led to slight increases in muscle mass but no significant strength gains. However, the most fit individuals in both groups showed little to no improvement, emphasizing the need for progressive overload and individualized programming. Despite its effectiveness for endurance and moderate strength gains, HIFT’s reliance on bodyweight, sandbags, and kettlebells limited maximal strength development, highlighting the necessity of heavier resistance for continued progress.
Purpose of the Study
This study aimed to:
- Evaluate whether HIFT produces superior adaptations in strength, endurance, and body composition compared to TMPT.
- Assess how initial fitness levels affect adaptation to military training.
- Provide insights into how training structure impacts performance outcomes for military personnel.
Subjects
- Total sample: 243 male conscripts (aged 18–28 years).
- Final study sample: 133 conscripts completed at least two measurement sessions:
- HIFT group (EXP): 66 conscripts (age 19 ± 1, body mass 73.7 ± 12.7kg, height 178 ± 7cm).
- TMPT group (CON): 67 conscripts (age 19 ± 1, body mass 73.3 ± 11.6kg, height 179 ± 6cm).
- Exclusions: 117 subjects were lost due to unit transfers or service cessation, and 6 dropped out due to lack of motivation.
Research Method
- 19-week intervention with performance tests at baseline (PRE), week 10 (MID), and week 19 (POST).
- Testing variables:
- Aerobic endurance: 12-minute run (total distance covered).
- Strength: Maximal voluntary isometric contraction (MVIC) for upper/lower body.
- Power: Seated medicine ball throw (SMBT) and standing long jump (SLJ).
- Muscular endurance: 1-minute push-ups and sit-ups.
- Body composition: Body mass, muscle mass, body fat %, and waist circumference (WC).
- Training volume:
- HIFT: 46 total hours (30 HIFT, 5 running, 3 calisthenics, 3 orienteering, 2 self-defense, 1 resistance training, 2 swimming).
- TMPT: 42 total hours (10 running, 13 ball games, 9 calisthenics, 3 orienteering, 2 self-defense, 3 resistance training, 2 swimming).
Findings
1. Aerobic Performance
- 12-minute run distance increased significantly in both groups but was superior in HIFT:
- HIFT: +11.6% (238 ± 310m, p < 0.001, ES: 0.79).
- TMPT: +5.7% (100 ± 276m, p = 0.008, ES: 0.33).
- Biggest gains were seen in the lowest fitness tertile (T1), with no improvements in the fittest individuals (T3).
- HIFT improved aerobic performance despite having 50% less running volume than TMPT, likely due to high-intensity circuit-based training.
2. Strength and Power
- Maximal voluntary isometric contraction (MVIC) improvements:
- Upper body (MVICupper): +3.8% (24 ± 70N, p = 0.001) in HIFT, no change in TMPT.
- Lower body (MVIClower): +5.0% (116 ± 408N, p = 0.02) in HIFT, no change in TMPT.
- Upper-body power (SMBT) improved in HIFT (+3.1%, 15 ± 38cm, p = 0.003), while TMPT declined (-2.2%, 14 ± 42cm, p = 0.013).
- No improvements in push-ups, sit-ups, or standing long jump (SLJ) in either group.
- Strength gains in HIFT were mostly neural adaptations, as progressive overload was limited by the equipment (sandbags, kettlebells).
3. Body Composition
- Body mass decreased in HIFT (-1.6kg, p = 0.001), while TMPT showed a muscle mass increase (+0.7kg, p < 0.001).
- Waist circumference (WC) decreased in HIFT (-1cm, p = 0.011), but TMPT saw no significant change.
- No significant group x time interaction in body fat percentage, but HIFT had a small decrease in body fat (-1.1kg, p = 0.004).
- Changes in body mass did not correlate with improved performance, suggesting enhanced oxygen utilization and running economy contributed to aerobic gains.
Conclusion
This study confirms that HIFT is an effective and time-efficient training method for improving soldiers’ aerobic fitness and strength, particularly for those with lower baseline fitness levels. The program’s high-intensity, circuit-based approach outperformed traditional endurance-heavy training despite lower total running volume. However, maximal strength development was limited due to inadequate progressive overload with kettlebells and sandbags, indicating that traditional resistance training with heavier loads is necessary for continued strength gains.
From a practical application standpoint, HIFT should be considered a viable alternative to endurance-heavy military training due to its superior aerobic adaptations in less time, but heavier resistance training should be incorporated to optimize strength development. Additionally, military training programs should prioritize individualized progression, particularly for highly fit individuals who may not respond well to general training protocols. Leaders should also recognize that low-volume, high-intensity training can be more effective than traditional endurance methods for improving combat readiness, provided that sufficient resistance is included. Future research should explore strategies to increase progressive overload in military settings while maintaining the time-efficient benefits of HIFT.
Bibliography
Helén, J., Kyröläinen, H., Ojanen, T., Pihlainen, K., Santtila, M., Heikkinen, R., & Vaara, J. P. (2023). High-Intensity Functional Training Induces Superior Training Adaptations Compared With Traditional Military Physical Training. Journal of Strength and Conditioning Research, 37(12), 2477–2483.