Effects of a Fifteen-week Off-season Period on Body Composition, Bone Health, and Physical Performance in Elite Female Futsal Players
A 15-week off-season period in elite female futsal players significantly increased lower-limb fat mass, decreased aerobic fitness and dynamic balance, and reduced lean mass, highlighting the need for individualized maintenance programs to counteract detraining effects on body composition and physical performance.
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In the world of elite sports, the calendar is not just a schedule of games; it is a cycle of intense physical stress followed by periods of rest. For athletes in high-intensity indoor team sports like futsal, the competitive season demands a body capable of explosive speed, rapid changes of direction, and sustained endurance. To maintain this peak condition, players rely on a constant stream of mechanical stress: the impact of their feet hitting the floor, the resistance of their muscles working against gravity, and the rhythmic demand of their hearts pumping blood. When the season ends, however, this cycle breaks. The structured training stops, and the body enters a period known as the off-season. While rest is necessary for recovery, science has long understood that the human body is an adaptive machine that responds to what it is asked to do. When the heavy lifting and running cease, the body begins to shed the specific adaptations it built to handle them. This process, often called detraining, is a natural biological response, but for elite athletes, the question remains: how much is lost during the long break, and does it matter for their health and future performance?
A team of researchers from universities in Spain set out to answer this question by observing a group of twenty-eight elite female futsal players from the top division of the Spanish league. These women, with an average age of twenty-six, had spent years competing at the highest level, training four times a week and playing official matches every weekend. The researchers wanted to see exactly what happened to their bodies after a fifteen-week break, a period significantly longer than the typical four-to-eight weeks seen in many other professional leagues. The team measured the players at the very end of their competitive season and then again just before their next pre-season training block began. They used advanced scanning technology to look inside the body, measuring how much fat and muscle was in specific areas, checking the density of the bones in the legs and spine, and testing how well the players could jump, run, stretch, and balance.
The results revealed a clear and measurable shift in the players' physical makeup. The most striking change occurred in the lower body, where the players gained a significant amount of fat mass in their legs. The fat in the right leg increased by roughly thirteen percent, while the fat in the left leg grew by over sixteen percent. At the same time, the muscle tissue in the left leg shrank by nearly four percent. This combination of gaining fat and losing muscle in the legs is a classic sign of detraining, suggesting that without the daily mechanical loading of sport, the body prioritizes storing energy over maintaining muscle tissue. The researchers also found that the players' aerobic fitness, or their ability to sustain high-intensity effort, dropped noticeably. Their performance on a shuttle-run test, which measures how fast they can run back and forth while recovering, fell by nearly six percent. This decline indicates that the heart and lungs had lost some of their efficiency, a change that happens relatively quickly when regular training stops.
Not every aspect of the players' physical condition changed, however. The ability to jump vertically, which relies on explosive power, remained largely the same, as did the flexibility of their hamstrings and lower back. This suggests that while the body loses some of its endurance and muscle mass, the basic ability to generate a quick burst of power and the range of motion in the joints are more resilient during a short break. Balance, a crucial skill for a sport that requires constant pivoting, showed a mixed picture. The players maintained their balance when reaching backward or to the side, but their ability to reach forward with their left leg decreased significantly. This specific loss of forward balance control points to a weakening in the muscles that stabilize the hip and knee, which are critical for preventing injuries when changing direction quickly.
The study also looked at the health of the players' bones, which are strengthened by the impact of running and jumping. While the measurements did not show a statistically significant drop in bone density, the data pointed in a consistent negative direction across all the areas tested. The bone mineral content in the right leg and the density in the pelvis both showed trends toward decline, with the changes being large enough to be of clinical concern even if they did not reach the strict threshold for statistical proof. This suggests that fifteen weeks without the heavy impact of futsal is enough to begin reversing the bone-strengthening effects of the sport. The researchers noted that the players' bone health might be at risk over the long term if this pattern repeats every year, especially given the unique hormonal and metabolic factors that affect female athletes.
Ultimately, the study paints a picture of a body that is highly responsive to its environment. When the intense demands of elite futsal are removed for fifteen weeks, the body adapts by becoming less muscular, carrying more fat in the legs, and losing some of its cardiovascular and balance capabilities. The findings do not suggest that the players are in danger, but they do highlight that the off-season is not a neutral pause; it is an active period of deconditioning. For coaches and sports scientists, the message is clear: a long break requires a carefully designed maintenance plan. To preserve the hard-won gains of the competitive season, athletes need to continue engaging in specific aerobic, strength, and balance activities, along with proper nutrition, even when they are not in official training. Without these targeted efforts, the body will naturally drift away from the peak condition required to compete at the highest level.
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