Josh L. Secomb

Relationships Between Lower-Body Muscle Structure and Lower-Body Strength, Power, and Muscle-Tendon Complex Stiffness

Abstract Secomb, JL, Lundgren, LE, Farley, ORL, Tran, TT, Nimphius, S, and Sheppard, JM. Relationships between lower-body muscle structure and lower-body strength, power, and muscle-tendon complex stiffness. J Strength Cond Res 29(8): 2221–2228, 2015—The purpose of this study was to determine whether any relationships were present between lower-body muscle structure and strength and power qualities. Fifteen elite male surfing athletes performed a battery of lower-body strength and power tests, including countermovement jump (CMJ), squat jump (SJ), isometric midthigh pull (IMTP), and had their lower-body muscle structure assessed with ultrasonography. In addition, lower-body muscle-tendon complex (MTC) stiffness and dynamic strength deficit (DSD) ratio were calculated from the CMJ and IMTP. Significant relationships of large to very large strength were observed between the vastus lateralis (VL) thickness of the left (LVL) and right (RVL) leg and peak force (PF) (r = 0.54–0.77, p < 0.01–0.04), peak velocity (PV) (r = 0.66–0.83, p < 0.01), and peak jump height (r = 0.62–0.80, p < 0.01) in the CMJ and SJ, as well as IMTP PF (r = 0.53–0.60, p = 0.02–0.04). Furthermore, large relationships were found between left lateral gastrocnemius (LG) pennation angle and SJ and IMTP PF (r = 0.53, p = 0.04, and r = 0.70, p < 0.01, respectively) and between LG and IMTP relative PF (r = 0.63, p = 0.01). Additionally, large relationships were identified between lower-body MTC stiffness and DSD ratio (r = 0.68, p < 0.01), right (LG) pennation angle (r = 0.51, p = 0.05), CMJ PF (r = 0.60, p = 0.02), and jump height (r = 0.53, p = 0.04). These results indicate that greater VL thickness and increased LG pennation angle are related to improved performance in the CMJ, SJ, and IMTP. Furthermore, these results suggest that lower-body MTC stiffness explains a large amount of variance in determining an athletes ability to rapidly apply force during a dynamic movement.

Time–Motion Analysis of a 2-Hour Surfing Training Session

PURPOSE To provide a descriptive and quantitative time-motion analysis of surfing training with the use of global positioning system (GPS) and heart-rate (HR) technology. METHODS Fifteen male surfing athletes (22.1 ± 3.9 y, 175.4 ± 6.4 cm, 72.5 ± 7.7 kg) performed a 2-h surfing training session, wearing both a GPS unit and an HR monitor. An individual digital video recording was taken of the entire surfing duration. Repeated-measures ANOVAs were used to determine any effects of time on the physical and physiological measures. RESULTS Participants covered 6293.2 ± 1826.1 m during the 2-h surfing training session and recorded measures of average speed, HRaverage, and HRpeak as 52.4 ± 15.2 m/min, 128 ± 13 beats/min, and 171 ± 12 beats/ min, respectively. Furthermore, the relative mean times spent performing paddling, sprint paddling to catch waves, stationary, wave riding, and recovery of the surfboard were 42.6% ± 9.9%, 4.1% ± 1.2%, 52.8% ± 12.4%, 2.5% ± 1.9%, and 2.1% ± 1.7%, respectively. CONCLUSION The results demonstrate that a 2-h surfing training session is performed at a lower intensity than competitive heats. This is likely due to the onset of fatigue and a pacing strategy used by participants. Furthermore, surfing training sessions do not appear to appropriately condition surfers for competitive events. As a result, coaches working with surfing athletes should consider altering training sessions to incorporate repeated-effort sprint paddling to more effectively physically prepare surfers for competitive events.

Associations Between the Performance of Scoring Manoeuvres and Lower-Body Strength and Power in Elite Surfers

The purpose of this study was to determine whether any significant associations were present between lower-body strength and power, and the performance of turning and aerial manoeuvres in elite surfing athletes. Eighteen competitive male surfers performed a battery of physical tests (countermovement jump (CMJ), squat jump (SJ), and isometric mid-thigh pull (IMTP)) during a single session, in addition to having their performance of turning and aerial manoeuvres ranked from highest to lowest. Significant associations were identified between turning manoeuvre ranking and; peak force in the CMJ, SJ and IMTP (ϱ=−0.737, p<0.01; ϱ=−0.856, p<0.01; ϱ=−0.683, p<0.01, respectively), as well as, peak velocity and jump height in the CMJ (ϱ=−0.560, p=0.02; ϱ=−0.529, p=0.02, respectively). No significant associations were identified between aerial manoeuvre ranking and any strength and power variables. These results suggest that surfing athletes that exhibit greater lower-body isometric and dynamic strength, and power also perform higher scoring turning manoeuvres during wave riding.

Comparison of Physical Capacities Between Nonselected and Selected Elite Male Competitive Surfers for the National Junior Team

PURPOSE To determine whether a previously validated performance-testing protocol for competitive surfers is able to differentiate between Australian elite junior surfers selected (S) to the national team and those not selected (NS). METHODS Thirty-two elite male competitive junior surfers were divided into 2 groups (S=16, NS=16). Their age, height, body mass, sum of 7 skinfolds, and lean-body-mass ratio (mean±SD) were 16.17±1.26 y, 173.40±5.30 cm, 62.35±7.40 kg, 41.74±10.82 mm, 1.54±0.35 for the S athletes and 16.13±1.02 y, 170.56±6.6 cm, 61.46±10.10 kg, 49.25±13.04 mm, 1.31±0.30 for the NS athletes. Power (countermovement jump [CMJ]), strength (isometric midthigh pull), 15-m sprint paddling, and 400-m endurance paddling were measured. RESULTS There were significant (P≤.05) differences between the S and NS athletes for relative vertical-jump peak force (P=.01, d=0.9); CMJ height (P=.01, d=0.9); time to 5-, 10-, and 15-m sprint paddle; sprint paddle peak velocity (P=.03, d=0.8; PV); time to 400 m (P=.04, d=0.7); and endurance paddling velocity (P=.05, d=0.7). CONCLUSIONS All performance variables, particularly CMJ height; time to 5-, 10-, and 15-m sprint paddle; sprint paddle PV; time to 400 m; and endurance paddling velocity, can effectively discriminate between S and NS competitive surfers, and this may be important for athlete profiling and training-program design.

Lower-Body Muscle Structure and Jump Performance of Stronger and Weaker Surfing Athletes

PURPOSE To identify whether there are any significant differences in the lower-body muscle structure and countermovement-jump (CMJ) and squat-jump (SJ) performance between stronger and weaker surfing athletes. METHODS Twenty elite male surfers had their lower-body muscle structure assessed with ultrasonography and completed a series of lower-body strength and jump tests including isometric midthigh pull (IMTP), CMJ, and SJ. Athletes were separated into stronger (n = 10) and weaker (n = 10) groups based on IMTP performance. RESULTS Large significant differences were identified between the groups for vastus lateralis (VL) thickness (P = .02, ES = 1.22) and lateral gastrocnemius (LG) pennation angle (P = .01, ES = 1.20), and a large nonsignificant difference was identified in LG thickness (P = .08, ES = 0.89). Furthermore, significant differences were present between the groups for peak force, relative peak force, and jump height in the CMJ and SJ (P < .01-.05, ES = 0.90-1.47) and eccentric peak velocity, as well as vertical displacement of the center of mass during the CMJ (P < .01, ES = 1.40-1.41). CONCLUSION Stronger surfing athletes in this study had greater VL and LG thickness and LG pennation angle. These muscle structures may explain their better performance in the CMJ and SJ. A unique finding in this study was that the stronger group appeared to better use their strength and muscle structure for braking as they had significantly higher eccentric peak velocity and vertical displacement during the CMJ. This enhanced eccentric phase may have resulted in a greater production and subsequent utilization of stored elastic strain energy that led to the significantly better CMJ performance in the stronger group.

Development and evaluation of a drop-and-stick method to assess landing skills in various levels of competitive surfers

The purpose of this study was to develop and evaluate a drop-and-stick (DS) test method and to assess dynamic postural control in senior elite (SE), junior elite (JE), and junior development (JD) surfers. Nine SE, 22 JE, and 17 JD competitive surfers participated in a single testing session. The athletes completed 5 drop-and-stick trials barefoot from a predetermined box height (0.5 m). The lowest and highest time-to-stabilization (TTS) trials were discarded, and the average of the remaining trials was used for analysis. The SE group demonstrated excellent single-measures repeatability (ICC = .90) for TTS, whereas the JE and JD demonstrated good single-measures repeatability (ICC .82 and .88, respectively). In regard to relative peak landing force (rPLF), SE demonstrated poor single-measures reliability compared with JE and JD groups. Furthermore, TTS for the SE (0.69 ± 0.13 s) group was significantly (P = .04) lower than the JD (0.85 ± 0.25 s). There were no significant (P = .41) differences in the TTS between SE (0.69 ± 0.13 s) and JE (0.75 ± 0.16 s) groups or between the JE and JD groups (P = .09). rPLF for the SE (2.7 ± 0.4 body mass; BM) group was significantly lower than the JE (3.8 ± 1.3 BM) and JD (4.0 ± 1.1 BM), with no significant (P = .63) difference between the JE and JD groups. A possible benchmark approach for practitioners would be to use TTS and rPLF as a qualitative measure of dynamic postural control using a reference scale to discriminate among groups.

Comparison of impact forces, accelerations and ankle range of motion in surfing-related landing tasks.

ABSTRACT This study aimed to describe the impact forces, accelerations and ankle range of motion in five different landing tasks that are used in training and testing for competitive surfing athletes, to assist coaches in the prescription of landing task progression and monitoring training load. Eleven competitive surfing athletes aged 24 ± 7 years participated, and inertial motion sensors were fixed to the anterior aspect of the feet, mid-tibial shafts, sacrum and eighth thoracic vertebrae on these athletes. Three tasks were performed landing on force plates and two tasks in a modified gymnastics set-up used for land-based aerial training. Peak landing force, resultant peak acceleration and front and rear side ankle dorsiflexion ranges of motion during landing were determined. The peak acceleration was approximately 50% higher when performing aerial training using a mini-trampoline and landing on a soft-density foam board, compared to a similar landing off a 50 cm box. Furthermore, the ankle ranges of motion during the gymnastic type landings were significantly lower than the other landing types (P ≤ 0.05 and P ≤ 0.001), for front and rear sides, respectively. Conclusively, increased task complexity and specificity of the sport increased the tibial peak acceleration, indicating greater training load.

Effects of unstable and stable resistance training on strength, power, and sensorimotor abilities in adolescent surfers

The purpose of this study was to investigate two different resistance-training interventions (unstable or stable) on strength, power, and sensorimotor abilities in adolescent surfers. Ten competitive female and male high school surfers were assessed before and after each of 2 × 7-week training intervention, using a within-subjects cross-over study design. Results for strength revealed no condition-by-time interaction or main effect for condition. However, there was a significant main effect for time, with significant strength gains post-training. There was a significant condition-by-time interaction for power exhibited as a significant decrease from pre- to post-training in the unstable condition, while the stable condition approached significant improvement. These results suggest that unstable and stable resistance training are both effective in developing strength in previously untrained competitive surfers, but with little effect on sensorimotor abilities. However, unstable training is inferior for the development of lower body power in this population.

Development and evaluation of a simple, multifactorial model based on landing performance to indicate injury risk in surfing athletes

PURPOSE To develop and evaluate a multifactorial model based on landing performance to estimate injury risk for surfing athletes. METHODS Five measures were collected from 78 competitive surfing athletes and used to create a model to serve as a screening tool for landing tasks and potential injury risk. In the second part of the study, the model was evaluated using junior surfing athletes (n = 32) with a longitudinal follow-up of their injuries over 26 wk. Two models were compared based on the collected data, and magnitude-based inferences were applied to determine the likelihood of differences between injured and noninjured groups. RESULTS The study resulted in a model based on 5 measures--ankle-dorsiflexion range of motion, isometric midthigh-pull lower-body strength, time to stabilization during a drop-and-stick (DS) landing, relative peak force during a DS landing, and frontal-plane DS-landing video analysis--for male and female professional surfers and male and female junior surfers. Evaluation of the model showed that a scaled probability score was more likely to detect injuries in junior surfing athletes and reported a correlation of r = .66, P = .001, with a model of equal variable importance. The injured (n = 7) surfers had a lower probability score (0.18 ± 0.16) than the noninjured group (n = 25, 0.36 ± 0.15), with 98% likelihood, Cohen d = 1.04. CONCLUSIONS The proposed model seems sensitive and easy to implement and interpret. Further research is recommended to show full validity for potential adaptations for other sports.

Single-leg Squat Progressions

ABSTRACTTHE EXERCISE TECHNIQUE FOR THE SINGLE-LEG SQUAT AND THE ASSOCIATED PROGRESSIONS ARE OUTLINED IN THIS ARTICLE. FIVE PROGRESSIONS ARE DESCRIBED, WITH INFORMATION PROVIDED TO ASSIST THE STRENGTH AND CONDITIONING COACH TO SELECT THE BEST MODALITY FOR EACH INDIVIDUAL ATHLETE.