Concurrent training in Youth Performance Sport; A Review
Background
The benefits of physical activity are well documented for youth – helping to develop both the physical fitness and the motor control necessary for more advanced movement skill in sport-specific environments. The World Health Organisation recommends a minimum of 60 minutes of moderate-high intensity activity each day for benefits to be realized (23). Beyond general physical activity, many young people partake in competitive sports to enjoy current participation, but also with a long-term approach to compete at high levels when more mature (14). Many sports demand actions that require power and strength but also require sustained efforts over a long period of time (aerobic endurance) (13). The quest for attaining these physical qualities independently is well-established, but doing so concurrently is less clear, particularly in youth. Combining multiple modes of training to induce simultaneous adaptations initially sounds quite appealing. However, youth frequently encounter busy schedules alongside school, organized and unorganized physical activity and increasing competition schedules. Adding more training to an already busy, growing organism may have its drawbacks. Furthermore, issues with concurrent training frequently see negative responses due to overreaching/overtraining (6). This should be a key consideration when applying concurrent training within a youth environment.13 studies were used in gaining an understanding of the effects on concurrent and single-mode training on youths. This review aims to identify effective strategies to employ concurrent training within predominantly endurance-based sports, whilst considering the wellbeing of those involved and the maturation of the athletes and then provide some practical takeaways and recommendations.
Table 1: Study Characteristics
CT = Concurrent Training
ET = Endurance Training
C. Age = Chronological Age
M = Method of training
W = Weeks
F = Frequency per week
Int = Intensity
S = Sets
R = Reps
HV = High Volume
LI = Low Intensity
HRM = Heart Rate Max
MAS = Max Aerobic Speed
Analysis
This brief review and analysis will look to summarise which methods of training see more favorable results towards either concurrent or endurance training.
Endurance: Concurrent Vs Endurance
Four studies reported the measure of V02 max within their study. Concurrent training reported only minor effects on aerobic endurance out of these studies. Five studies reported exercise economy as seeing only trivial effects from concurrent training compared to endurance training. 10 studies employed the use of a time trial to assess athletic performance – from these studies, concurrent training saw the most favorable improvements.
Strength/Power: Concurrent Vs Endurance
3 studies employed the use of a counter-movement jump to assess lower body power outputs. These studies reported more favorable results towards concurrent training to improve power compared to only endurance training. All concurrent training groups who utilized strength training (either body or free weight) saw greater increases in lower and upper body strength outputs. 3 Studies using concurrent training with plyometric methods saw improvements in lower body power but trivial effects on lower body strength.
Discussion; Practical Application and Limitations
According to the results within this review, strength qualities are important characteristics for youth endurance athletes. Generally, muscular strength is an important factor effecting athletic performance in youth, contributing to exercise efficiency as well as movements and skills which require power and repeated efforts (10). For sports where aerobic endurance is the primary athletic quality (swimming, rowing, running, cycling), concurrent training can used effectively in a balanced, well-structured exercise program to see favorable improvements in athletic performance in youth athletes. This is contrary to research within adults where the “interference effect” is commonly seen within concurrent training programs – seeing less favorable improvements in the desired training outcomes (7). Before extrapolating any firm conclusions from this initial concept, some considerations should be made and some context applied. Mikkola et al., (2012)found that untrained adults saw improvements in muscular hypertrophy, maximal strength output and cardiovascular endurance during a concurrent training program. From the literature in this review, youth included throughout all studies were regularly training for their respective sport however, not necessarily completing regular training included in the concurrent training groups (resistance/plyometric training) (15). Therefore, the youth in these studies can be considered untrained regarding the strength training elements of concurrent training. The improvements seen as a result of concurrent training in youth may therefore be attributed to the stimulus being new to the individuals, like that seen in untrained adults. Further research may be needed to assess the effects of concurrent training between trained and untrained youth athletes.
While improvements can be seen from concurrent training in untrained youth and adult athletes, gains are not as great as those seen from block-style periodization, both in trained and untrained participants (22). This raises the question around what style of training may be best for youth athletes. Many adopt the stance that a varied approach to long-term youth athletic development may be best for motor development, injury reduction as well as psychosocial development in youths (13, 19). If the desired result of training is purely outcome based, looking at simply improving physical characteristics of youth to compete and win, then block-style training focusing on a single quality at a time may be the best method. However, if the approach is more holistic, focusing on long-term development, playing sport for the social rewards and development of the all-round athlete, concurrent training may be the preferred method. It will very much case-specific on what approach is best, depending on the ability of the athlete, their maturation and the goals on the training program. A limitation of this review is that it does not consider the multi-sport athlete. Sports included in the review tend to require early specialization if long-term success is the goal for an individual as they require high volumes of training each week (12). As alluded to earlier, concurrent training saw the greatest improvement in overall athletic performance meaning this approach may be best for the multi-sport athlete. Furthermore, overuse injuries account 53% of all injuries within adolescents (20), further strengthening the argument that a variety of training methods (or sports) may be advantageous for youths as opposed to singular modes of training.
A key consideration should be the negative effects of concurrent training and how these may be exacerbated within a youth population. While an argument exists for concurrent training to prevent overuse injuries, this method should be used with caution considering burnout and overreaching. The primary reason that the “interference effect” is seen during concurrent training is due to the high volume of training (7). It is well documented that youths experiencing Peak-Height Velocity (PHV) (girls 11-13, boys 13-15) can be more susceptible to overuse and acute injuries in organized sport (13). Furthermore, females see increases in knee abduction moments during PHV, further increasing chances of knee injury during this period (17). Extreme caution should be used when adding in elements of concurrent training to youths who are approaching, during or exiting PHV. This may present an argument for training with a singular focus during this phase. Knowing that the “window” for strength and hypertrophy training is post-PHV (13), it may be appropriate to focus on endurance qualities of athletes experiencing PHV while avoiding the risks associated with loading in this phase. Variety can still be implemented through less stressful training modalities, mobility and motor control, for example.
Conclusion
Concurrent training can be a useful tool for the development of multiple physical qualities within youth populations. As ever, considerations around the goal for the athlete, training age, biological age and training load should guide all decision-making processes - prioritising the wellbeing of the athlete. Care should be used when training around PHV – adapting training volume and methods during this phased in-order to minimize the chance of injury and overreaching.
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