Effect of preventive exercises on hamstring and calf muscle characteristics

The current literature on prevention of muscle injuries in basketball is limited and there are no clinical outcome studies in elite female basketball. Previous studies among football players have shown that preventive exercises can be successful in the prevention of muscle injuries. These exercises seem to induce changes in muscle characteristics e.g. lengthening of fascicle length (FL) and alteration of pennation angle (PA), which are measured by ultrasound. There are some concerns about the reliability of ultrasound measurements as it is an investigator-dependent procedure and only allows indirect calculation of FL and PA. With diffusion tension magnetic resonance imagining (DT-MRI) it is possible to directly assess these muscle characteristics with a high reliability. For this reason two randomized controlled trials will be performed among dutch male and female basketball players. The basketball players will be asked to perform a preventive exercise for 3 months (or no exercise for the control group) whereafter alterations within their hamstring (male) and calf (female) muscle architecture will be assessed through DT-MRI measures. Volunteers will be recruited in the Netherlands.

Evaluate the efficacy of exercise prevention programs on hamstring and calf injuries by assessing muscle characteristics using DT-MRI.

All outcomes will be measured at two timepoints, namely baseline and 3 months follow-up. The outcomes will be measured as described above in primary and secondary outcomes.

Participants will be randomized to either i) Nordic exercises (NHE) ii) Diver exercises or iii) no-training specific hamstrings intervention. Duration, sessions per week and sets/repetitions for the hamstring prevention exercises are based on previous reports with a total duration of 3 months. Instruction of the exercises will be given through the caregiver with written and video documentation. These hamstring exercises are well described in the current literature and examples are presented on YouTube (NHE: https://www.youtube.com/watch?v=qPRZcNx_C0A; Diver: https://www.youtube.com/watch?v=3JwxQy2OSus)

For the calf prevention study (CIP) female basketball players will be randomized to i) modified eccentric Alfredson’s heel drop exercises; ii) concentric heel drop exercises or iii) no-training specific calf intervention. Basketball players are instructed to perform each repetition in 2 seconds.2 Duration, sessions per week and sets/repetitions for calf prevention exercises are based on previous reports with a total duration of 3 months. These calf exercises are well described in the current literature and examples are presented on YouTube (Alfredson’s heel drop exercise: https://www.youtube.com/watch?v=ge3XDjjKofk)