The effects of cross-training on fitness and injury in women.

Background: As combat arms occupations become available to women, adequate muscular strength and aerobic endurance will be essential for the completion of physically demanding job-related tasks. Therefore, in addition to US Army Physical Readiness Training, Soldiers will often engage in their own personal physical fitness training programs.

Purpose: To evaluate fitness and injury outcomes for women participating in personal cross-training programs compared to women performing one mode of training or having no personal fitness program.

Methods: Demographics, physical training activities, physical fitness, and injuries were obtained from surveys administered to female Soldiers in an infantry division. Women were categorized into the following 4 groups based on their personal physical fitness program: cross-training (CT), running only (R), weight training only (WT), and no personal fitness program (NPF). An ANOVA was used to compare physical training, health behaviors, and physical fitness across groups. A χ² test was used to compare injury rates between fitness programs. Risk (%), risk ratios (RR) and 95% confidence intervals (95% CI) were used to determine injury risk.

Results: A total of 620 women completed the survey and indicated whether or not they had a personal fitness program (cross-training, n=260; running only, n=93; weight training only, n=86; no personal fitness program, n=181). Average age and body mass index was 26.2±5.8 years and 24.5±3.3 kg/m² respectively with no differences between the 4 fitness groups. The cross-training group had higher physical performance on the muscular endurance (push-ups and sit-ups) portion of the Army physical fitness test (APFT) when compared to the 3 other groups (CT 42 push-ups vs (R 38, WT 35, NPF 36)); (CT 68 sit-ups vs (R 63, WT 62, NPF 62)). For the aerobic endurance (2-mile run) portion of the APFT, the cross-training group had higher performance when compared to those with no personal fitness program (CT 17.4 minutes vs NPF 18.5 minutes). Overall, 53% of female Soldiers sustained an injury over a 12-month period. All injury rates and lower extremity injury rates among women with a cross-training personal fitness program were not different from the other personal fitness programs. Those performing cross-training were 2.6 and 2.1 times more likely to experience a running related injury when compared to those in the weight training and no personal fitness group, respectively. On the other hand, women performing cross-training were 65% less likely to experience a lifting/moving heavy objects related injury when compared to the weight training only group.

Conclusions: Women who participated in a cross-training program for personal physical fitness training had higher muscular endurance compared to the other fitness groups and higher aerobic endurance when compared to the no personal fitness group. There were no differences for all injuries and lower body injuries between cross-training and other fitness programs. Cross-training may be the best option for improving physical fitness when compared to just one mode of fitness training.