Despite an improved aerobic endurance, still high attrition rates in initially low-fit recruits-results of a randomised controlled trial

Background

Low baseline fitness of recruits entering basic military training (BMT) is associated with an increased risk of musculoskeletal injuries (MSIs) and attrition from training.

Objective

To determine the effects of a pre-training conditioning program (PCP) on aerobic endurance, incidence of musculoskeletal injuries (MSIs), and attrition rates in BMT of a special infantry unit of the Netherlands Armed Forces.

Participants

Recruits were considered eligible for this study when they were ‘low-fit’ at the start of BMT (time to complete a 2.7-km run ≥ 12′23″).

Interventions

‘Low-fit’ recruits were deferred to a seven to twelve week—depending on the time between two consecutive training platoons—PCP consisting of functional training to improve several fitness domains. The control (CON) group started regular BMT without delay.

Results

Forty-nine recruits were included in this study; 26 in the PCP-group and 23 in the CON-group. Recruits who followed the PCP started BMT with better aerobic endurance than the CON-group who started BMT immediately (2.7 km run timings: PCP 11′32″, CON 13′16″). The risk of dropout was lower in the PCP-group (incidence density ratio (IDR) 0.63, 95%CI 0.32; 1.26), but dropout due to training-related MSIs was more frequent (IDR 1.23, 95%CI 0.32; 4.76 (per-protocol 0.94, 95%CI 0.24; 3.63), without statistically significant differences between the groups.

Conclusion

Although a PCP was effective to improve aerobic endurance in low-fit recruits to return to meet pre-enlistment fitness criteria, we could not demonstrate an effect on dropout from military training.

Trial registration

Dutch trial register Trial NL6791 (NTR6977) https://www.trialregister.nl/trial/6791.

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Low baseline fitness of recruits is associated with musculoskeletal injuries and dropout from military training.

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A pre-training conditioning program was capable of improving physical fitness in low-fit recruits.

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However, dropout from training remained high, perhaps due to common other causes.

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Future research should focus on identifying these physical, social and mental factors, and their interactions.

A pre-training conditioning program to increase physical fitness and reduce attrition due to injuries in Dutch Airmobile recruits: Study protocol for a randomised controlled trial

Background

Low baseline fitness of recruits entering basic military training is shown to be associated with an increased risk of musculoskeletal injuries (MSIs) and attrition of military training. This in turn leads to an increased demand for health care, increased health care costs and decreased personnel occupancy rate of military units.

Design

Study protocol for a randomised controlled trial.

Objective

To determine the effects of a pre-training conditioning program on cardiovascular endurance, incidence of overuse injuries, and attrition rates in Dutch Airmobile recruits undertaking initial military training.

Setting

Royal Netherlands Army, Air Assault Brigade military training course.

Participants

Recruits are considered eligible for this study when they are ‘low-fit’ at the start of the initial military training. Time to complete a 2700 m run test in ≥12′23’’ is used as selection criteria.

Interventions

We use a complex system approach to cover multiple domains of MSI prevention and optimise intervention circumstance; a pre-training conditioning program, training staff support, process-focused culture and health accountability. The pre-training conditioning program contains functional training to improve mobility, power, agility, lower and upper body strength and cardiovascular endurance. Cardiovascular endurance will be targeted both by endurance training and high intensity interval training.

Main outcome measurements

Outcome measures include cardiovascular endurance, injury incidence, attrition rates, lost training days due to injuries, and implementation fidelity of the PCP.

Trial status

Recruitment of participants commenced April 18, 2018 and final results are expected in August 2019.

Trial registration

Dutch trial register www.trialregister.nl/=trial/6791.