Student Blog 03: Sleep, Nutrition, and Injury Risk in Adolescent Athletes - A Narrative Review
Lorcán Mason is a MRes Student at ATU Donegal.
This review examines the effects of sleep and nutrition on the risk of injury in adolescent athletes. Sleep is considered an active regulatory process and plays a crucial role in the proper functioning of the brain, cognitive performance, and physiological functions. It is essential for the recovery process and contributes to growth, repair, regeneration, and immunity. The literature suggests that sleep has implications for athletic performance, recovery, injury risk, and mental well-being. The relationship between sleep and recovery in athletes can be understood by considering three key factors: sleep duration (including napping), sleep quality (absence of sleep disorders or disturbances), and sleep phase (timing of sleep during the light-dark cycle). During adolescence, the pressures of psychosocial and societal factors may lead to poor sleep health and reduced capacity for recovery. Sleep deficiencies have negative effects on health and are associated with increased mortality and disease risk. Insufficient sleep duration and disturbances are risk factors for adverse health, recovery, and injury risk in athletes. For sleep to have a restorative effect, it must meet an individual's sleep needs in terms of duration and quality, which vary with age. Sleep duration is influenced by environmental factors and individual characteristics, making it challenging to define an "optimal" sleep pattern. Circadian rhythms also play a role in sleep duration, with the timing of sleep in the light cycle being important. Chronotype, which reflects individual circadian rhythmicity, may change during adolescence due to increased sleep pressure and environmental factors that increase evening alertness. While an individual's chronotype is mainly determined by genetics, environmental and societal factors also have an impact.
Sleep Adaptation during Adolescence
Cross-sectional research has demonstrated that the distribution of chronotype shifts towards the evening chronotype during adolescence, and then reverts back to earlier chronotypes after maturation. The literature has shown that elite athletes require approximately 8.3 hours of sleep in order to feel rested. However, adolescent athletes on average only achieve around 6.3 hours of sleep, indicating a discrepancy between sleep recommendations and actual sleep duration. The process of sleep-wake cycle development occurs during adolescence, leading to adaptations in sleep regulation during this phase. These adaptations increase the ability to tolerate sleep pressure (due to reduced adenosine accumulation) and are influenced by the maturation of physiological, psychological, and cognitive functioning, as well as delays in circadian rhythmicity. This combination of factors creates an environment that is conducive to inadequate sleep, particularly influenced by external factors associated with adolescence (as shown in Figure 1). Consequently, there is a gradual decrease in the amount of time spent asleep between the ages of 15 and 18, with research indicating a decrease of approximately 1.5-3 hours during this period.
Injury Risk during Adolescence
Adolescence denotes the phase of transition in one's life characterized by the process of maturation, which is influenced by the onset of puberty. Puberty, being unique to each individual, encompasses a wide range of inter-individual variations in the state of maturation, impacting both physical and psycho-social development. Maturation status plays a crucial role in enhancing locomotive competencies, with both linear (accumulation of strength capabilities) and non-linear (accumulation of co-ordinative capabilities) factors influencing training adaptations in adolescent athletes. Additionally, growth and maturation are energy-demanding processes where energy intake significantly affects the synthesis of new tissue and the deposition of nutrients into this tissue. Consequently, nutrition assumes a pivotal role in facilitating proper maturation, training adaptation, and recovery. The occurrence of injuries during training or competition poses an inherent risk for athletes, impeding their ability to train effectively or achieve optimal performance. This risk is particularly pertinent for adolescent athletes, as injuries not only jeopardize their athletic progression but also impact their overall health and enjoyment of participating in sports. The realm of elite youth sport further compounds the challenges faced by adolescents, given the heightened training volume, increased training intensity, and demanding competition schedules associated with it. Consequently, the heightened exposure to elite sports is likely to elevate the risk of musculoskeletal injuries, particularly during periods of rapid growth. Furthermore, recent years have witnessed an upsurge in injury prevalence among adolescent athletes, with reported injury rates ranging from approximately 1.4 to 6.4 per 1000 hours of training and approximately 22.4 per 1000 hours of competition. Hence, it is imperative to identify modifiable risk factors that can aid in recovery and mitigate injury risk. Both sleep and nutrition are considered modifiable factors that facilitate recovery in athletes, emphasising their relevance in injury mitigation interventions.
Relationship between Sleep, Nutrition, and Injury Risk in Adolescent Athletes
Despite the correlation established between sleep and injury risk in athletic populations, there has been a lack of comprehensive research conducted on adolescent athletes. Previous studies utilizing subjective questionnaires have indicated that adolescent athletes who sleep less than 8 hours per night are 1.7 times more likely to sustain an injury. Additionally, it has been found that reducing sleep duration during periods of intense training increases the likelihood of injury by 2.25 times. Moreover, a decrease in sleep volume alone leads to a 1.46-fold increase in injury risk, while specifically obtaining less than 8 hours of sleep results in a 1.31-fold increase in injury risk. Although there is limited research on this topic concerning adolescent athletes, associations have been discovered between diet quality, sleep, and injury risk. Despite the significance of proper nutrition during adolescence and its interaction with sleep and recovery, there is a lack of research investigating the relationship between sleep, nutrition, and injury risk in adolescent athletes. In a study involving 340 elite adolescent Swedish athletes, researchers utilized subjective questionnaires and found that athletes who met recommended nutrition intake reduced their injury risk by 64%. Furthermore, it was reported that athletes who slept for more than 8 hours per weeknight decreased their injury risk by 61%.
Conclusion
As it has been established, the role of both sleep and nutrition is of utmost importance when it comes to recovery and the risk of injury in athletic populations. It is crucial to understand that maturation is a process that requires a significant amount of energy, especially considering the high energy demands and training requirements of adolescent athletes. Additionally, it is well-known that there is an increased risk of injury during periods of peak growth and/or training intensity. Therefore, it is imperative to not underestimate the significance of the recovery process.
Furthermore, it is important to consider the specific sleep adaptations that occur during adolescence. These adaptations include increased sleep pressure tolerance and circadian phase delay. These changes in sleep patterns, combined with the current research findings indicating that compromised sleep and an inadequate diet may increase the likelihood of injury occurrence, highlight the clear negative impact of poor sleep on injury risk in adolescent athletes. This underscores the need for further investigation into the relationship between sleep, nutrition, and injury risk.
Moreover, research also suggests that adequate nutrition plays a positive role in both sleep quality and injury risk reduction. The current evidence demonstrates that an inadequate diet is associated with a decreased likelihood of injury occurrence. Therefore, it is evident that proper nutrition is essential for promoting optimal recovery and minimizing the risk of injuries in adolescent athletes.
Given the complexity and importance of this topic, it is crucial that further research is conducted to explore the impact of objective sleep measures and specific nutritional interventions on injury risk in adolescent athletes. By investigating these factors in a more detailed manner, we can gain a deeper understanding of the underlying mechanisms and develop targeted interventions to optimize recovery and reduce injury risk in this population.
In conclusion, the relationship between sleep, nutrition, and injury risk in adolescent athletes is a multifaceted and critical area of study. The existing research clearly demonstrates the negative impact of poor sleep on injury risk, as well as the positive role of proper nutrition. However, there is still much to learn in order to fully comprehend the intricacies of this relationship. Therefore, further research is warranted to expand our knowledge and inform evidence-based interventions for the benefit of adolescent athletes.
Full Text Link
Mason, L., Connolly, J., Devenney, L.E., Lacey, K., O’Donovan, J. and Doherty, R., 2023. Sleep, nutrition, and injury risk in adolescent athletes: a narrative review. Nutrients, 15(24), p.5101.
Available at: https://doi.org/10.3390/nu15245101