MedXFit-Effects of 6 months CrossFit® in sedentary and inactive employees: A prospective, controlled, longitudinal, intervention study.

Background and Aims: Sedentary behavior and physical inactivity are associated with musculoskeletal disorders (MSD). Muscle and mobility enhancing training is recommended to promote musculoskeletal fitness and prevent MSD. A functional fitness program emphasizing the importance of musculoskeletal fitness is provided by CrossFit®. However, data from long-term CrossFit® interventions assessing measures of musculoskeletal fitness in sedentary and inactive individuals does not exist.

Methods: Thi s prospective, controlled study investigates the effects of 6 months CrossFit® training (2×60 min/week) in inactive adults (in terms of <2 muscle or mobility enhancing training sessions per week) with predominantly sitting or standing occupations. 91 participants were initially assessed, 2 were excluded, 55 self-selected for intervention (IG), and 34 for the control group (CG). Primary endpoint was a change in mobility (Functional Movement Screen score). Secondary endpoints were changed in strength (maximum isometric strength in kg; Dr. Wolff BackCheck®), and well-being (WHO-5 score). Key exploratory endpoints were changes in back-issue measures (pain intensity, limitation, and frequency).

Results: 39 participants of IG and 31 of CG completed the evaluation after 6 months. The IG improved significantly more ( p  < 0.001) compared with the CG in the FMS ( η ² = 0.58), trunk extension ( η ² = 0.46), trunk flexion ( η ² = 0.47), trunk lateral flexion left ( η ² = 0.41), trunk lateral flexion right ( η ² = 0.42), upper body push ( η ² = 0.4), upper body pull ( η ² = 0.25), hip extension left ( η ² = 0.18), and hip extension right ( η ² = 0.4). Change of WHO-5 scores did not significantly differ between groups ( p  = 0.55; η ² = 0.01). Exploratory analysis of back-issue data showed a higher decrease for pain intensity, limitation, and frequency in the IG compared with the CG.

Conclusion: This study proves for the first time within the scope of a prospective, controlled study the broad benefits of CrossFit® in inactive adults doing predominantly sedentary work.