The importance of sprinting speed in many sports, including contact sports such as rugby, football, and ice hockey, is undeniable. However, there is another variable called sprinting momentum that is often overlooked. It’s unfortunate because the value of sprinting momentum in contact sports can very well mean the difference between scoring and not scoring. In a study this month in the Journal of Strength and Conditioning Research, the usefulness of momentum was compared to that of speed.
Sprint momentum is a derived value, which means it is the product of two or more other values – in this case, speed and bodyweight. When you combine the velocity of the object with its mass, you will get a number that represents the force required to stop that object from moving. A higher momentum has clear applications to sports in which players make contact with one another. It’s no wonder positions requiring more contact tend to have larger players.
There is an optimum interplay between speed and weight that maximizes momentum. To some extent, they antagonize one another. At some point getting heavier means your top speed will diminish, but your momentum may still increase, so long as you are gaining more weight than you are losing speed. Since both speed and momentum are important in contact sports, the question becomes which one should athletes focus on maximizing?
In this study the researchers looked at national rugby playersin the junior (under twenty years old) and senior (over twenty years old) levels. They examined the interplay between positions and levels, and then followed some of the athletes for two years to see how speed and momentum changed and affected performance.
The first part of the results – the difference between speed and movement amongst various players – was specific to rugby, although it can be extrapolated to other sports. Speed was roughly the same between the junior and senior level players. By contrast, momentum changed significantly between levels. Further, backs were faster than forwards, but forwards had greater momentum, indicating a higher demand for contact. So speed and momentum can be used to determine position and skill or age level, at least for rugby.
The second part was the examination of changes over time. This one takes less imagination to deduce the ramifications for other contact sports. The juniors, who transitioned to senior level players over the two years, experienced greater physical changes, which was no surprise. There seemed to be a peak in speed around the time of this transition, which took place at age twenty, but momentum continued to improve. In other words, the athletes got heavier without getting any faster or slower as they transitioned to the senior level. This was an important difference between the two levels, and likely made the senior players better, especially as forwards.
For contact sports like rugby, momentum may be a better single determinant of performance than either speed or weight alone. This becomes especially true in positions with a lot of contact. Fortunately, it’s also a stat that is easy for the average coach to test, and can help inform decisions as players transition into different levels or positions.
1. Matt Barr, et. al., “Long-term training induced changes in sprinting speed and sprint momentum in elite rugby union players,” Journal of Strength and Conditioning Research, DOI: 10.1519/JSC.0000000000000364
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