In football (soccer), balancing physically demanding training regimens with effective recovery strategies is crucial for optimal performance. Teams often play multiple games a week, making it critical to manage training stimuli and recovery effectively. This article explores which sports science measures matter most in this sport.
Reactive Strength
Reactive strength is a critical capacity for all football players, representing the body's ability to rapidly switch from an eccentric action to a concentric action. This ability is essential in movements such as sprinting, jumping, and changing direction.
Reactive Strength Index (RSI)
The Reactive Strength Index is a metric for assessing an individual's reactive strength ability. The RSI is calculated by dividing jump height by ground contact time, aiming to understand how much time an athlete spends in the air versus on the ground. This measure helps in programming training to enhance an athlete's reactive strength.
RSI Testing Methods
Several methods can be used to calculate RSI:
Drop Jump: Athletes jump off a standardised box height.
Incremental Drop Jump: Different box heights to evaluate plyometric abilities.
Rebound Jump Test: Countermovement jump followed by a rebound jump, eliminating the need for a box.
Ten-Five Testing: Involves a countermovement jump followed by 10 bilateral repeated hops. RSI score is averaged from the best five reps.
In the video below, I detail these testing methods, along with our other measures that matter, on the Global Performance Insights YouTube channel. This video is from this series in collaboration with Output Sports that discusses measures that matter across different sports.
Benchmark data for RSI can be used to guide training programmes, particularly for players needing improvement in their fast stretch-shortening cycle abilities. The benchmarks below have been proposed by Eamonn Flanagan, from a mixture of research and anecdotal evidence. However, it is always important to consider your data within the context of your own population.
Velocity
Velocity-based training (VBT) is increasingly used in team sports to balance training intensity with needed recovery. Unlike traditional percentage-based training, which relies on a fixed one-repetition maximum (1RM), VBT uses an autoregulation approach, adjusting intensity based on the athlete's daily capacity. We also discussed this in our post in this series on American Football.
Measuring Velocity
Velocity-based training measures lifting output by the speed of the bar, providing real-time feedback on training intensity. As load increases, the concentric velocity decreases linearly. Tools like Output Sports enable feedback, driving competition and intent in the weight room while ensuring appropriate training intensity adjustments. You can see a real life example of this in the video above, at approx. 5:35, with England Men's Football team using the Output Sports leaderboard to drive competition within the group.
Hamstring Strength
Hamstring strength is vital in football for performance and reducing injury risk. The Nordic hamstring exercise is noteworthy in both performance enhancement and injury prevention.
Nordic Breakpoint Angle
Measuring the Nordic breakpoint angle provides insights into hamstring strength. During the exercise, the breakpoint is where the hamstrings can no longer maintain knee flexion, leading to a rapid torso drop. This indirectly measures eccentric hamstring strength.
Hamstring Flexibility
Hamstring flexibility is another factor influencing injury risk. The passive straight leg raise test is the gold standard for measuring this flexibility. Studies, such as this one in the Journal of Sport Sciences, have shown that athletes with greater hamstring flexibility often perform better in other physical measures important in football.
Tracking Flexibility and Strength
Tracking these metrics together throughout the season using systems like Output Sport’s online hub allows for comprehensive analysis, helping to correlate strength and flexibility measures and track how an athlete is responding to their programme.
Final Thoughts
Football demands a range of physical capacities, and managing these through effective measures and training programmes is vital. While there is a multitude of measures that matter in football, this post has focused on four of them. Reactive strength, velocity, hamstring strength, and flexibility are four key measures that can guide sports science support for football players. Tools like Output Sports provide the data needed for these analyses, facilitating informed decision-making.
Frequently Asked Questions (FAQs)
What is the Reactive Strength Index (RSI)?
RSI is a measure of an athlete's reactive strength, calculated by dividing jump height by ground contact time.
How does velocity-based (VBT) training differ from traditional training?
What is the Nordic breakpoint angle?
Why is hamstring flexibility important in football?
This article is supported by Output Sports. For more information about their technology, visit their website.
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