Effect of Four Weeks Detraining on Strength, Power, and Sensorimotor Ability of Adolescent Surfers

INTRODUCTION

Surfing is a high skill demand sport that requires a considerable amount of time in a variety of ocean conditions to help develop the fundamental techniques. It has been reported that recreational and competitive surfers spend as much as 6.6 ± 4.4 and 12.3 ± 2.8 hours of surfing per week, respectively [20]. In comparison, resistance training has been reported as total durations of 1.5 ± 2.7 and 0.5 ± 0.6 hours per week for recreational and competitive surfers, respectively [20]. With this in mind, resistance training does not appear to be a priority within the surfing community, as more time is spent in the water to improve surfing ability. Anecdotally, surf coaches and adolescent surfers believe spending more time surfing, in the absence of resistance training, is a sufficient stimulus to maintain physical capabilities. Due to the inconsistency of the environment, the priority of the athlete is to surf when the conditions are favourable and resistance train when the conditions are poor [6]. This surf mantra might make it challenging for surfing athletes to be consistent with a periodised resistance-training program because they are busy chasing favourable surfing conditions. Currently, there are no research published on the effects of detraining on strength, power, and sensorimotor abilities in competitive surfing athletes. Therefore, it is imperative to investigate adaptations from resistance training, and then cease training to determine whether surfing in the absence of resistance training is a sufficient stimulus to maintain physical characteristics.

Previous research documented that adolescents participating in a resistance training program not only benefits health and psychological well-being, but also important for growth and motor skill development [8]. Over the years the numbers of adolescents participating in sports has increased, thus increasing the rate of sport related injuries [8]. Therefore, incorporating an appropriate resistance training program under qualified supervisions may be advantagous for reducing the likelihood of sports related injuries [8, 10]. Furthermore, greater physical qualities [e.g., strength and power] have been reported to associate with surfing performance [28, 30]. Recent evidence revealed physical performance reflected selection from a group of elite junior surfers to represent Surfing Australia National Junior Team at the International Surfing Association World Junior Surfing Championship [33]. Collectively, these studies demonstrated the importance of physical qualities for surfing performance and using a group of junior surfers distinguished physical performance among selected and non-selected elite junior surfers. Adequate resistance-training stimulus has been shown to elicit positive neuromuscular adaptations [9,13]; conversely, detraining negatively affects strength and power parameters within a relatively short period [2, 12, 17]. It is important to note detraining [cessation of resistance training] has potential negative implications for athletic performance, whereas a well-planned tapering phase may augment performance variables such as strength, power, and endurance [26]. Previous studies have highlighted decrements in strength and power as a result of detraining following completion of a resistance training program in various populations: children [12], sedentary [2], college-age women [32], and power athletes [16]. However, little is known with regards to the effect of detraining on performance parameters in adolescent surfers.

Faigenbaum et al. [12] demonstrated that children [7-12 y] significantly decreased upper [-19.3%] and lower body [-28.1%] strength over an eight-week detraining period. Izquierdo et al. [17] demonstrated that four weeks of detraining subsequent to 16 weeks of resistance training had a significant negative effect on strength [-9%] and power [-17%] in physically active men. In another study, Staron et al. [32] demonstrated that college-age women significantly decreased leg press [-32%] and leg extension [-29%] strength following 30-32 weeks of detraining. Furthermore, Andersen et al. [2] reported strength, power, and muscle cross-sectional area [CSA] decreased to pre-training levels after three months of detraining in sedentary men. Conversely, Hortobagyi et al. [16] demonstrated power athletes’ strength level did not significantly alter following 14 days of detraining, however, Type II muscle fibre area decreased 6.4%. Interestingly, Santos and Janeira [27] were able to demonstrate that the explosive power was maintained during 16 weeks of detraining in adolescent male basketball players. Collectively, with the exception of Hortobagyi et al. [16] and Santos and Janeira [27], these studies have demonstrated a decrease in strength [2, 12, 27], power [2, 17], and muscle CSA [2, 16], however, it is important to note that different individuals respond and adapt to training stimuli differently. Specifically, the studies by Hortobagyi et al. [16] and Santos and Janeira [27] represent the potential for a population with longer training history to be able to decrease or not experience the decrements in physical capacity seen in populations with lower training history.

Postural control and dynamic balance are critical for the sport of surfing; however, there is a lack of scientific evidence regarding the effect of detraining on sensorimotor ability for adolescent competitive surfers. Drop landing from a pre-determined height followed by a motionless posture is relevant to the sport of surfing as the athletes are required to transition from a dynamic to a static position with the time to stabilization [TTS] currently the accepted test for this ability [36]. This method quantifies the time an athlete takes to stabilize their posture within 5% of body mass upon landing. In addition, this test also quantifies landing force from a vertical direction as this might demonstrate whether detraining affects the ability to effectively attenuate landing forces. Wikstrom et al. [36] reported vertical TTS method established fair reliability with an intraclass correlation coefficient [ICC] measure of 0.78 with a 95% confidence interval of 0.59-0.90. Additionally, drop landing might suggest whether this method is sensitive and valuable to detect small changes of sensorimotor ability for adolescent surfers. For example, during a floater manoeuvre, surfers launch themselves on top of the face of the wave, then drop land to the bottom in front of the broken wave. If the surfer is able to stabilize and control their posture quickly and efficiently, they are more likely to land successfully and transition to the next manoeuvre.

While there is a considerable amount of literature on the positive adaptations from acute and long-term resistance training in young athletes [7, 8, 11-13], it is uncertain whether adolescent surfers are able to maintain physical performance with surfing alone. Therefore, the purpose of this study was to determine the magnitude of changes in physical performance over a four-week detraining period during which the athletes completed no resistance training.

MATERIALS AND METHODS

This study investigated the impact of detraining on strength, power, and sensorimotor ability in adolescent surfers following seven weeks of periodized resistance training. Performance parameters of power [vertical jump height; VJH], maximal isometric strength [isometric mid-thigh pull; IMTP], and sensorimotor ability [time to stabilization during a drop and stick [DS]; TTS] pre-test results were determined from the conclusion [post-test] of a seven-week training block while post-test results were measured at the start [pre-test] of a second seven-week training block. In other words, the four-week washout period between two seven-week training blocks was used to assess the effect of a detraining period. Four weeks cessation of resistance training was based on the participants’ school break schedule. Athletes performed three countermovement jumps to self-selected depth, three IMTP, and five DS trials. The best trial for each variable was used for further analysis.

Statistical Analysis

In order to determine if there were any significant differences from pre- to post-test, pair t-tests were used to compare anthropometry and performance results. All statistical analyses were completed using SPSS for Windows, version 22 software [SPSS Inc., Chicago, IL, USA] with criterion level of significance set at p ≤ 0.05. Cohen’s effect sizes [ES] were calculated as ES=mean change divided by the standard deviation of the sample scores [3]. The magnitudes of the ES’s were evaluated as trivial < 0.2; small 0.2-0.5; moderate 0.5-0.8; or large > 0.8 [5].

RESULTS

Average strength, power, and sensorimotor ability performance are presented in Table (1) and percent changes for pre to post measures are shown in Figs. (1-3). Power performance measures significantly decreased for vertical jump peak velocity [-3.7%, p<0.001, ES =-0.51], vertical jump height [-5.3%, p=0.037, ES=-0.40], isometric absolute peak force [-5.5%, p= 0.012, ES= -0.-21], and relative peak force [-7.3%, p= 0.003, ES=-0.47]. Sensorimotor ability, via time to stabilization, significantly increased [61.4%, p=0.004, ES=0.99]. In addition, there was no significant change in relative peak landing force during the DS [-2.3%, p>0.05, ES=-0.06]. There was no significant change observed for relative vertical jump peak force [1.8%, p>0.05, ES=-0.06].

DISCUSSION

The purpose of this study was to investigate the effects of a period of cessation of resistance training or detraining on power, strength, and sensorimotor ability subsequent to short-term resistance training. The main finding of this study was that cessation of resistance training for four-weeks negatively affected performance parameters for competitive adolescent surfers. This study provides evidence that surfing, in the absence of resistance training, is not a potent enough stimulus to maintain or increase physical capabilities. Recently, Loveless and Minahan [20] reported that recreational and competitive surfers spend between 2-11 and 9.5-15 hours surfing per week, respectively, while participation in resistance training was reported as 0-2 hours per week. This finding is in line with Mendez-Villanueva et al. [24], indicating that the majority of surfers’ training is performed in the water. The adolescent surfers in our study surfed an average of 12-19 hours per week. It is possible that the higher number of surf hours in the current study might suggest adolescent surfers have more time and access and engage for fun rather than purposeful training in the water.

In response to four weeks of detraining, power measures for the vertical jump of peak velocity and jump height significantly decreased by 3.7%, with a moderate magnitude [ES=-0.1] and 5.3%, with a small magnitude [ES=-0.40], respectively. Declines in vertical jump height in the present study are consistent with Faigenbaum et al. [12], who reported a 4.0% decrease subsequent to eight weeks of detraining in adolescents. However, these findings conflict with Santos and Janeira [27], who reported that male adolescent basketball athletes were able to maintain explosive power following 16 weeks of detraining. An explanation for this conflict might be due to a higher volume of plyometrics involved in basketball practice throughout the 16-week detraining period. For example, basketball is a sport that involves continuous use of the stretch shortening cycle during activities such as lay-ups, dunks, rebounding, changes of direction, or blocking shots throughout practice. Although surfers perform similar absorption, braking, and propulsion phase activities during wave riding, the volume is less due to the nature of the sport as wave riding represents only 3.8-8.0% of total activity [14, 22, 23]. Therefore, it might be concluded that higher plyometric volume during basketball practice provides adequate stimulus to maintain power in adolescent basketball athletes compared to adolescent surfers. In another study, Hortobagyi et al. [16] reported that 14 days of detraining did not significantly decrease vertical jump height in power athletes. A possible explanation for this might be that athletes with a longer training age are able to maintain explosive power for an extended time or that acute training cessation was not adequate to induce an effect on explosive power in power athletes.

Lower body isometric strength measures for absolute and relative peak force demonstrated significant decreases of 5.5% [p=0.012] with a small magnitude [ES=-0.21] and 7.3% [p=0.003], also of a small magnitude [ES=-0.47], respectively. These findings are consistent with Faigenbaum et al. [12], who reported that detraining subsequent to eight weeks of resistance training significantly decreased lower body strength [-28.1%] in children ranging from 7-12 years. The magnitude of strength loss in the Faigenbaum study is much greater compared to the present study. Although the duration of their detraining period was double that of the current study, the differences in strength loss are quite large. It has been previously shown that lower physical level athletes have a larger window for adaptation [4]; hence, a possibility for the large decline might be similar for strength losses and gains in younger athletes compared to those with higher physical capacities.

Interestingly, Hortobagyi et al. [16] reported significant decreases in Type II fibre area [6.4%] in power athletes over four weeks of detraining, however, there was no significant decrease identified in lower body strength [-0.9%]. Although it has been documented that muscle CSA is associated with strength gains [21], their findings further support the contention that highly trained athletes are able to maintain their strength following an acute detraining period compared to those with lower strength levels. An interesting finding from the current study is that detraining had a greater effect on muscular strength compared to power output. Similarly, Faigenbaum et al. [12] demonstrated a greater loss in strength than power during eight weeks of detraining. Conversely, Izquierdo et al. [17] reported that Basque ball athletes demonstrated a greater loss in power [-17.0%] compared to muscular strength [-9.0%] after four weeks of detraining. Basque ball involves a diverse of sports played with one’s bare hand, a racket, a wooden bat or basket, against a wall [17]. Collectively, these studies strongly suggest the effect of detraining on power and strength appears to be dependent on training age as well as the duration of detraining. Furthermore, consideration of the type, intensity and volume of physical activity undertaken during the detraining period must also be taken into account regarding the magnitude of changes resulting from detraining [12]. In other words, physical activities such as basketball, soccer, or volleyball place a greater demand on the neuromuscular system compared to activities that limit stretch shortening cycle loading from jumping and landing.

Although surfing is performed in a dynamic environment, the surfer is relatively stable as the speed of the board increases [25]. In response to sensorimotor ability [TTS during drop and stick] following four weeks of detraining, the athletes took significantly [p=0.004] longer to stabilize from a drop landing. However, relative peak landing force was not significantly [p>0.05] altered. Interestingly, strength performance significantly decreased with an associated increase in TTS, however, athletes were able to maintain relative peak landing force.

CONCLUSION

In light of these findings, adolescent surfers experienced a reversal effect when resistance training was discontinued for four weeks. These results demonstrate that surfing, in the absence of resistance training, is not a potent enough stimulus to maintain performance parameters. The results of this study will increase awareness within the surfing community of the deleterious impact of detraining on strength, power, and sensorimotor ability. Competitive adolescent surfers with a relatively low training age should strive to maintain consistent resistance training in conjunction with surf training to avoid the negative decrements in power, strength, and sensorimotor ability, as these are likely to reduce physical capabilities. Therefore, by continuing resistant training in adolescent surfers, training age increases and continued gains in strength, power, and sensorimotor abilities can be continued and therefore more likely to be able to contribute to increased performance during surfing or decreased injury risk and ability to tolerate surfing training loads. Regarding the safety and recommendations for resistance training progressions, junior surfing athletes should seek a qualified strength and conditioning coach and refer to the Strength Training for Young Athletes book for appropriate training intensity, volume and correct exercise technique [19].

REFERENCES