Those who coach younger athletes often to do not have access to strength and conditioning facilities, nor do they have designated training sessions dedicated to physical preparation outside of regular practice times. With these limitations set in place, it is common for coaches to budget sections of practice time to work on strength and power training. Coaches will use calisthenics and plyometrics on the field which can be very effective for improving performance and reducing injury risk.
Growing in popularity as an “injury prevention” exercise is the Nordic hamstring curl. We’ve written several posts on some of the novel research published on this exercise over the last few years. There definitely appears to be a relationship between eccentric hamstring strength and reduced hamstring strains. What remains to be studied about the Nordic hamstring exercise is the acute effects that this has on hamstring function. This is particularly important for coaches who prescribe this exercise as part of the warm-up period, or earlier on in practice. This is especially important because the Nordic hamstring curl has been included in the FIFA-11 warm-up protocol which is a very popular protocol used by many amateur and youth soccer coaches throughout the world.
A new study published in the Journal of Strength and Conditioning Research by Bazuelo-Ruiz et al. (2015) evaluated changes in hamstrings muscle activity via electromyograms (EMG) and maximal eccentric and concentric torque output after each set of 5×6 Nordic hamstring exercises in ten amateur, college-aged soccer players. The results showed that both maximal eccentric and concentric torque of the hamstrings was reduced between 8-17% after the first set, and progressively decreased with each subsequent set. Muscle activity during the descent phase progressively increased throughout the sets. During the ascent phase biceps femoris muscle activity (not semimembranosis and semitendonosis) was reduced from the start of exercise during latter sets of repetitions.
Given the high physical demand of this exercise and the amount of fatigue it causes in the hamstrings, the authors caution coaches to consider programming this exercise towards the end practice or as a home-based protocol. This is because hamstring injuries often occur under the presence of fatigue and by performing this exercise before training, fatigue will be induced before much of the running and change of direction takes place in practice. Thus, athletes may be at an increased risk of injury when performing such a high volume of this exercise early on in practice.
Bazuelo-Ruiz et al. (2015) Predicting maximal dynamic strength from the load-velocity relationship in squat exercise. Journal of Strength and Conditioning Research. Ahead of Print.