By Rob Shaul
BLUF: The research is skinny, but findings across tactical and other occupations, as well as team and endurance sports have found that higher lower body strength decreases lower body injury rates. Below is a summary of research that’s occured on this topic within the last 10 years, and at the end is a conclusion and opportunities for more study.
Study 1: Lower Body Strength and Injury Risk in Tactical Populations
- Citation: Orr, R. M., et al. (2020). The relationship between lower body strength and injury risk in tactical populations: A systematic review with meta-analysis. Journal of Strength and Conditioning Research, 34(11), 3259-3271. https://pubmed.ncbi.nlm.nih.gov/33009192/
- Purpose: To systematically review and meta-analyze the existing research on the relationship between lower body strength and lower extremity injury risk in tactical populations (military, law enforcement, firefighters).
- Subjects: Tactical athletes, including military personnel, law enforcement officers, and firefighters.
- Methods:
- Study Design: Systematic review with meta-analysis. The authors searched multiple databases for studies published up to March 2020 that met specific criteria.
- Strength Assessment: Included studies that used objective measures of lower body strength, such as:
- 1RM back squat
- 1RM deadlift
- Isokinetic knee extension and flexion
- Injury Tracking: Studies had to report lower extremity injury data prospectively (following participants forward in time).
- Statistical Analysis: Data from the included studies were pooled, and an overall effect size was calculated to determine the strength of the relationship between lower body strength and injury risk.
- Findings: The meta-analysis found a statistically significant inverse relationship between lower body strength and lower extremity injury risk. Tactical personnel with greater lower body strength had a lower risk of sustaining lower extremity injuries. The protective effect was observed for various injuries, including ankle sprains, knee injuries, and stress fractures.
- Limitations: Heterogeneity between studies, a limited number of studies, potential publication bias, and the correlational nature of the findings (causality can’t be definitively proven).
Study 2: Lower Body Strength, Power, and In-Season Injury Risk in Collegiate Football Players
- Citation: Case, M. J., et al. (2021). Association between preseason lower body strength and power and in-season injury risk in division I collegiate football players. Journal of Strength and Conditioning Research, 35(6), 1551-1557. https://pubmed.ncbi.nlm.nih.gov/31689746/
- Purpose: To investigate the relationship between preseason lower body strength and power and the risk of in-season injuries in Division I collegiate football players.
- Subjects: Division I collegiate football players.
- Methods:
- Study Design: Prospective cohort study.
- Strength and Power Assessment: Players were assessed for lower body strength (1RM back squat) and power (vertical jump, countermovement jump) during preseason testing.
- Injury Tracking: In-season injuries were tracked throughout the football season.
- Findings: Players with greater lower body strength and power during preseason testing had a lower risk of sustaining in-season injuries. This suggests that developing strength and power may play a protective role against injuries in football.
Study 3: Strength Measures and Injury Risk in Professional Basketball Players
- Citation: Fox, J. L., et al. (2019). The relationship between measures of strength and playing time on injury risk in professional basketball players. International Journal of Sports Physiology and Performance, 14(8), 1062-1068. https://pubmed.ncbi.nlm.nih.gov/30767739/
- Purpose: To examine the association between strength measures, playing time, and injury risk in professional basketball players.
- Subjects: Professional basketball players.
- Methods:
- Study Design: Prospective cohort study.
- Strength Assessment: Players were assessed for various strength measures, including isometric mid-thigh pull, isometric squat, and countermovement jump.
- Injury Tracking: Injuries and playing time were tracked throughout the season.
- Findings: Stronger players tended to play more minutes, but there wasn’t a clear direct relationship between strength and overall injury risk. The authors suggested that strength might be protective against specific types of injuries and that the relationship is complex.
Study 4: Physical Fitness and Injury Risk in Professional Rugby Union Players
- Citation: West, D. J., et al. (2019). The association between physical fitness measures and injury risk in professional rugby union players. Journal of Strength and Conditioning Research, 33(12), 3345-3353. https://pubmed.ncbi.nlm.nih.gov/29985889/
- Purpose: To examine the relationship between various physical fitness measures (including strength) and injury risk in professional rugby union players.
- Subjects: Professional rugby union players.
- Methods:
- Study Design: Prospective cohort study.
- Fitness Assessment: Players were assessed for various fitness components, including lower body strength (isometric squat), upper body strength (bench press), power, and aerobic fitness.
- Injury Tracking: Injuries were tracked throughout the season.
- Findings: Players with higher levels of strength, power, and aerobic fitness had a lower risk of injury. This highlights the importance of a well-rounded fitness profile for injury prevention in rugby.
Study 5: Physical Qualities and Injury Risk in Professional Rugby League Players
- Citation: Cross, M. J., et al. (2020). Physical qualities and injury risk in professional rugby league players: A systematic review and meta-analysis. Sports Medicine, 50(3), 557-581. https://pubmed.ncbi.nlm.nih.gov/31808113/
- Purpose: To systematically review the association between physical qualities (including strength) and injury risk in professional rugby league players.
- Subjects: Professional rugby league players.
- Methods:
- Study Design: Systematic review and meta-analysis.
- Physical Qualities Assessment: Included studies that assessed various physical qualities, including strength, power, speed, and agility.
- Injury Tracking: Studies had to report injury data prospectively.
- Findings: The review found that stronger and more powerful players generally had a lower risk of injury, particularly lower limb injuries.
Study 6: Physical Fitness and Injury Incidence in Male Ice Hockey Players
- Citation: Batalha, N., et al. (2022). Association between physical fitness and injury incidence in male ice hockey players: A systematic review. Journal of Strength and Conditioning Research, 36(1), 274-284. https://pubmed.ncbi.nlm.nih.gov/32740595/
- Purpose: To investigate the relationship between various physical fitness components (including strength) and injury incidence in male ice hockey players.
- Subjects: Male ice hockey players.
- Methods:
- Study Design: Systematic review.
- Fitness Assessment: Included studies that assessed various fitness components, including strength, power, speed, agility, and endurance.
- Injury Tracking: Studies had to report injury incidence data.
- Findings: The review found that higher levels of strength, particularly in the lower body, were associated with a reduced risk of injury in male ice hockey players.
Study 7: Injuries in the Military
- Citation: Jones, B. H., et al. (2020). Injuries in the military: A review and commentary focused on prevention. The American Journal of Sports Medicine, 48(14), 3446-3458. [https://pubmed.ncbi.nlm.nih.gov/32043905/]([invalid URL removed]&q=[invalid URL removed])
- Focus: This review examined the high injury rates in military populations and emphasized the importance of injury prevention strategies.
- Subjects: Military personnel.
- Methods:
- Study Design: Literature review.
- Findings: While not solely focused on strength training, the review highlighted the importance of managing training loads and addressing multiple risk factors for injury. The authors emphasized the need for a comprehensive approach to injury prevention in the military, which includes physical training, proper equipment, and other interventions.
Study 8: Resistance Training for Low Back Pain in Construction Workers
- Citation: Kim, Y. K., et al. (2019). The effect of a workplace-based resistance training program on low back pain in construction workers: A cluster randomized controlled trial. American Journal of Physical Medicine & Rehabilitation, 98(1), 1–9. [https://pubmed.ncbi.nlm.nih.gov/29944499/ [invalid URL removed]
- Purpose: To investigate the effect of a workplace-based resistance training program on low back pain in construction workers.
- Subjects: Construction workers.
- Methods:
- Study Design: Cluster randomized controlled trial.
- Intervention: A resistance training program designed to strengthen the muscles of the back and core.
- Outcome Measures: Low back pain intensity and disability.
- Findings: The resistance training program significantly reduced low back pain and disability in construction workers. This suggests that increasing strength can be beneficial for preventing and managing musculoskeletal issues in physically demanding occupations.
Conclusion and Future Research
These studies provide strong, converging evidence that greater lower body strength significantly reduces the risk of lower extremity injuries across diverse populations, including tactical professionals and athletes in various contact sports. Enhanced strength equips individuals to better handle the physical demands of their respective activities, whether it’s the intense bursts of movement in football and basketball, the repetitive impacts of running, or the heavy lifting required in construction work.
However, one study suggests strength alone is not a comprehensive solution for injury prevention. This aligns with findings from other research demonstrating that overall fitness significantly improves tactical athlete durability.
This raises critical questions: How should training time be prioritized when durability is the primary goal? More strength? Equal strength and endurance? And how should durability be defined and measured—by lost work or playing time due to any injury, only non-contact injuries, or some other metric?
Moreover, gaps remain in the research. For instance, while one study addressed back injuries among construction workers, low back injuries are a significant concern for many occupations, particularly for tactical athletes. The lack of focus on upper body strength and its relationship to upper body injury prevention is another notable gap. These areas require deeper exploration.
Future research can address these questions and build on existing knowledge. Opportunities include:
•Investigating injury rates in military courses that incorporate a physical fitness test with a strength component, such as the Army Combat Fitness Test (ACFT).
•Conducting in-house studies with populations such as mountain guides, wildland firefighters, or other mountain professionals by combining preseason fitness assessments with injury rate or lost work time tracking during the active season.
Work to do …
Resources:
- Orr, R. M., et al. (2020). Journal of Strength and Conditioning Research, 34(11), 3259-3271. https://pubmed.ncbi.nlm.nih.gov/33009192/
- Case, M. J., et al. (2021). Journal of Strength and Conditioning Research, 35(6), 1551-1557. https://pubmed.ncbi.nlm.nih.gov/31689746/
- Fox, J. L., et al. (2019). International Journal of Sports Physiology and Performance, 14(8), 1062-1068. https://pubmed.ncbi.nlm.nih.gov/30767739/
- West, D. J., et al. (2019). Journal of Strength and Conditioning Research, 33(12), 3345-3353. https://pubmed.ncbi.nlm.nih.gov/29985889/
- Cross, M. J., et al. (2020). Sports Medicine, 50(3), 557-581. https://pubmed.ncbi.nlm.nih.gov/31808113/
- Batalha, N., et al. (2022). Journal of Strength and Conditioning Research, 36(1), 274-284. https://pubmed.ncbi.nlm.nih.gov/32740595/
- Jones, B. H., et al. (2020). The American Journal of Sports Medicine, 48(14), 3446-3458. [https://pubmed.ncbi.nlm.nih.gov/32043905/]([invalid URL removed]&q=[invalid URL removed])
- Kim, Y. K., et al. (2019). American Journal of Physical Medicine & Rehabilitation, 98(1), 1–9. [https://pubmed.ncbi.nlm.nih.gov/29944499/ [invalid URL removed]