Association between anthropometry,upper extremity strength,and sprint and endurance paddling performance in competitive and recreational surfers

Abstract

This study investigated the correlations with anthropometry, upper extremity strength, and surfboard paddling performance in recreational and competitive surfers. Twenty-nine recreational and competitive male surfers were assessed for height, mass, relative arm span, relative seated height, relative biacromial width, and skinfolds (Sum7). The upper extremity strength variables assessed were the relative 1RM pull up and 1RM dip. The surfboard paddling variables assessed were a 15 m sprint-paddling test and a 400 m endurance-paddling water-based test. Pearson correlation analysis and independent t-tests were used to compare differences between groups and determine the significant correlations between variables. Sum7 and relative arm span were correlated with speed in all paddling efforts meanwhile the sprint-paddling ability was correlated with the upper extremity strength. Significant differences between competitive and recreational surfers exist in relative arm span and endurance paddle performance. The strong relationships between the physical variables can be used by sports coaches and support staff to influence talent identification, training, and nutrition programs.

Keywords

Kinanthropometry talent identification paddling water sport

Introduction

Competitive surfing is an international professional water sport. Competitive surfing success is determined by judging criteria that evaluates the surfer’s ability to catch and ride the best waves while executing innovative and athletic maneuvers in the most critical parts of the wave (i.e. closest to where the wave is breaking). Surfing competitions take place in a variety of ocean conditions. The type of wave (i.e. reef, sand, point, beach), the weather and tide conditions at the time of each heat all influence the surfing activity significantly.^1–3 This is especially true of factors including the amount of waves caught, time spent riding waves, and time spent paddling.

Despite the variability of conditions, time and motion analysis (TMA) of both competitive and recreational surfing reveals that surfing can be accurately characterized as an intermittent sport.^1,3–5 From the research analyzing competitive surfing, paddling dominates the activity characteristics of competitive surfing heats with actual time spent wave riding to be surprisingly low.^1,3–5 For instance, Mendez-Villanueva et al.⁴ found wave riding duration to be only 3.8% of the total surfing time, whilst Meir et al.¹ reported 5% and Farley et al.³ 8%. Meanwhile, paddling accounted for 44%,³ 51.4%,⁴ and 54%¹ of heat time and no activity (i.e. stationary lying or sitting on board) represented 35%,³ 42.5%,⁴ and 28%¹ respectively of the total time over the aforementioned studies. Considering the three previous studies^1,3,4 together, it appears that although competitive surfers are judged on their wave riding, it accounts for only a small portion of total activity, with about half of an entire competitive heat spent paddling.

The majority (∼60% in Mendez-Villanueva et al.⁴ and ∼80% in Farley et al.³) of the paddling bouts are all less than 20 s. Mendez-Villanueva et al.⁴ found that ∼25% of all the paddling bouts were less than 10 s and ∼35% between 10 and 20 s duration. Interestingly, Farley et al.³ found that ∼60% of all the paddling bouts were less than 10 s and ∼20% between 11 and 20 s duration. The substantial differences in these two findings can be attributed to the aforementioned factors affecting competitive surfing heats (e.g. type of wave (i.e. reef, sand, point, beach), the weather and tide conditions). However, in common is the large amount of relatively short, repeated bouts of paddling and it suggests that surfing can be considered a sport requiring multiple short duration intermittent paddle efforts.^1,3

Sprint paddling appears to be an important aspect of the surfing competition. High paddling velocity enables surfers to gain a positional advantage over other competitors during a heat and ensures fast entry speed into waves, enhancing the opportunity for the execution of a greater amount of maneuvers that will increase the judges’ score.^4,6–8 This has been reinforced by studies demonstrating competitive adult surfers being superior in sprint paddling when compared to competitive junior surfers.⁸ Bearing in mind the repeated effort and prolonged nature of surfing activity,^1,3,4 endurance paddling ability is also very likely to be a highly relevant physical quality⁷ when assessing the paddling ability.

In paddling actions (surfboard, paddleboard, swimming), athletes “pulls” and then “pushes” their body over and through the water surface. This means that their distal segment (e.g. hand) is fixed. By definition, this makes it a closed kinetic chain (CKC) activity^9,10 or, at the very least, a quasi-CKC activity when accounting for fluid movement around the hand. Previous investigations have used stationary paddle ergometers (i.e. open kinetic chain (OKC)) to determine the sprint and endurance paddle performance with conflicting results in discriminating between higher and lower performing surfers.^1,6,7 Evaluating endurance paddling ability in water (i.e. 400 m time trial) with surfers will provide greater context validity and along with being more practical, has been shown to effectively discriminate between higher and lower performing surfers.^11,12 With regard to strength assessments in this investigation, CKC strength exercise assessments may possess greater context validity for sports that predominately involve CKC neuromuscular activity¹³ as surfboard paddling does. CKC exercises are the opposite of OKC exercises in that the terminal segment cannot move freely or is restrained e.g. where an athlete applying force does not move.⁹ Examples of this relating to the upper extremity (UE) include the pull up and dip. Hence, it is worthwhile to examine the utility of the pull up and dip as CKC measures of UE maximal strength involving surfboard paddling.^8,12

To date, few studies have examined the potential relationship between anthropometric variables with paddling performance although arm span has been found to have a significant correlation with sprint paddle performance.⁸ No studies have considered the anthropometric effects on the endurance paddling performance. Considering the importance of the anthropometric factors like arm span and seated height in swimming,^14,15 it stands to reason that these variables will also be of importance to the surfboard paddling performance. Sheppard et al.⁸ is also the only study to our knowledge that has investigated an upper strength quality (pull up) relationship with surfboard paddling. Strong associations (r = 0.88–0.94) were found between relative upper body strength in the pull up and sprint paddle time and peak velocity over 5, 10, and 15 m.⁸ As mentioned above, the association between upper body pulling strength and endurance paddling was not considered. We were also unable to find any research investigating an upper body pushing strength movement (e.g. dip) on the paddling performance. Bearing in mind the significance of strength to both speed and power^16–23 and endurance,^24–27 this seems worthwhile to investigate. As strength has been shown to be a valid discriminator between performance levels in sports and disciplines ranging from rugby league to ice hockey,^28–31 it is important to determine whether this also applies to upper body strength and the sport of surfing.

With this in mind, the purpose of this study was to identify (i) relationship of anthropometric variables with both sprint and endurance paddling performance; (ii) relationship of the upper body strength qualities (pull up and dip) with both sprint and endurance paddling performance, and (iii) differences in anthropometric, strength, and paddling characteristics between recreational and competitive surfers. The information derived from this study is useful in guiding talent identification programs and training and nutrition programs for competitive surfing.

Method

Experimental approach to the problem

To assess the association between anthropometry, strength, and paddling performance, this study employed a correlation analysis within a group of adult male surfers. The correlation analysis was explored in two ways: the whole cohort and an adult male competitive group (COMP) within the cohort. COMP consisted of adult male surfers who had competed in Australian open boardriders club competitions, World Qualifying Series (WQS), or World Championship Tour (WCT) events. The remainder of the cohort was adult male recreational surfers (REC) who had a minimum of 4 years surfing experience. As this study was conducted in conjunction with Surfing Australia’s High Performance Center, it was designed to identify correlations that may assist COMP surfers improve their performance and to assess differences between COMP and REC anthropometric and paddling variables, which may help developing surfers. REC surfers’ correlations were not included in the study due to relevance to the goals of the study. They were also not included due to uncertainty as to whether these correlations could assist performance of either COMP or REC surfers.

Subjects

Twenty-nine male surfers participated in this study. As mentioned, the subjects were divided into COMP (n = 13, 176.9 ± 5.5 cm, 76.2 ± 8.7 kg)) or REC (n = 16, 177.7 ± 8.6 cm, 77.0 ± 10.9 kg)) groups based on the level of surfing competition. All the subjects received a clear explanation of the study. This included risks and benefits of participation. If after the explanation, the individual decided not be included in the analysis it would not negatively affect any current or future competitive opportunities or team selection. All subjects or their parent or guardian provided written informed consent. The study procedures were approved by the Human Ethics Committee at Edith Cowan University (Perth, Australia), and procedures conformed to the Code of Ethics of the World Medical Association (Declaration of Helsinki).

Procedures

Anthropometry

All the subjects were assessed for height, mass, relative arm span (arm span / height), relative seated height (seated height / height), relative biacromial width (biacromial width / height) and the sum of seven skinfolds. The sum of seven skinfolds was determined after the measurement of the triceps, sub scapulae, biceps, supraspinale, abdominal, quadriceps, and calf skinfold using a Harpenden skinfold caliper (British Indicator, UK). A composite ratio of body mass divided by the sum of seven skinfolds was then determined to reflect the amount of mass that is made up of lean tissue, termed the lean mass index (LMI),³² modified from original methods.³³ All the tests were conducted by a practitioner certified by the International Society for the Advancement of Kinanthropometry whose Typical Error of Measurement (%TEM) was 2.4% for skinfold measurements and 0.3% for all other measures.

Upper extremity strength

The subjects performed a warm up consisting of two sets of specific callisthenic and dynamic stretching exercises emphasizing upper body and trunk activity, lasting 10 min in total. After the warm up, the athletes commenced the pull up testing procedure first. This involved 5 repetitions with bodyweight followed by 4, 3, 2, and 1 repetitions with an increasingly greater external load. The external load was increased by suspending certified plate weights from a standard lifting belt worn around the waist for every decrease in repetitions. After these repetitions, the athletes performed only single repetitions with additional external load attached to their waists with 2–3 min of rest provided between repetitions. Once a failed lift occurred as defined by our movement and tempo standards (outlined below), the successful weight lifted in the previous lift was recorded as the subject’s 1RM. External load was increased by 1.25 to 10 kg between sets depending on the strength levels of the subjects, speed of concentric movement, and relative body mass. This testing procedure was then repeated in the exact same manner for the 1RM dip test.

To ensure reliability, distinct anatomical markers, movement speeds, and movement standards were used in the evaluation of the subjects’ pull up and dip performance. These pull up and dip testing procedures have been validated from the protocol developed by Coyne et al.³⁴ For the pull up, the testing protocol entailed subjects holding a fully flexed shoulder with extended arms for 2 s (to eliminate any slight jumping off the floor, stretch shortening cycle movement, or lack of shoulder flexion) before beginning their pulling action. To ensure a successful repetition, the subjects’ proximal inferior aspect of the mandible must have passed the horizontal plane of the pull up bar (e.g. the technique cue used was to “beach the jaw on the bar”). The subjects were then required to return to the initial position taking 4 s to complete the repetition.

For the dip, the testing protocol required the subjects to begin supported on the parallel bars in a fully extended elbow position. From this position, subjects lowered themselves over 4 s to a “depth” point where the bicep made contact with the forearm greater than the subjects’ combined 2nd and 3rd digit width from distal biceps tendon. This “depth” point was marked on each subjects’ forearm. To complete a successful repetition, the subjects were then required to return to the initial support position. When assessed in the aforementioned manner, the relative pull up (Intra-class Correlation (ICC) 0.96, Typical Error (TE) 0.03, Typical Error as CV (%CV) 2.22), and relative dip (ICC 0.97, TE 0.04, %CV 2.41) appear to be highly reliable.³⁴

Sprint and endurance paddling

Paddle testing was performed in an outdoor 25 m swimming pool. This allowed for simple outline of distances for the subjects, and control for the potential effect of ocean conditions like tides and currents. Each subject performed the test on their own surfboard and wore surfing boardshorts to provide context validity.

The subjects executed a paddling warm-up made up of 200 m of low-intensity paddling, followed by a specific sprint paddling warm-up of 4 × 15 m sprint paddling efforts at 60%, 70%, 80%, and 90% volitional effort on ∼2-min intervals. After 2 min rest, the subjects completed two maximal effort sprint-paddling time-trials (i.e. 2 × 15 m) to determine the maximum sprint paddling performance with the best of the two trials being their final result. The sprint paddle efforts were commenced from a stationary, prone lying, floating position.

Using a purpose-built horizontal position transducer (I-REX, Southport, Australia) attached to the back of each subjects’ boardshorts, kinematic data were gathered and kept for analysis on a personal computer. The position transducer recorded a time-stamp for each 0.02 m of displacement, thereby allowing determination of sprint times from the start to 5 m, 10 m, and 15 m, and by differentiation to calculate peak sprint paddle velocity (PVel). This procedure has been validated with surfboarding paddling in a pool and proven to have high measures of reliability (ICC 0.82–0.99, TE 0.01–0.11, %CV 0.52–2.99) for all the four measures.^11,35

The timed endurance paddle test was performed over a 20 m up and back course in the same pool, using two pool lane widths, so that nonstop paddling of 400 m could be accomplished. The paddling test was conducted with small buoy markers at both ends of the 20 m distance. This meant the subjects paddled 20 m and completed a 180° turn at each end around the buoy, until 400 m was completed. The time to finish the endurance paddle test was used for calculation of each subjects’ average velocity (AvVel), and was intended to reveal their endurance capabilities in the specific context of surfboard paddling. This 400 m timed endurance paddle test appears to be highly reliable (ICC 0.99, TE 9.21, %CV 2.01).¹²

Statistical analyses

From the anthropometric measures, 1RM upper body strength tests, and paddling tests, a correlation analysis was performed on both the COMP and REC groups and on the cohort as a whole. Correlations were designated as trivial (0–0.1), low (0.1–0.3), moderate (0.3–0.5), high (0.5–0.7), very high (0.7–0.9), and practically perfect (0.9–1).³⁶ Comparisons of the difference between COMP and REC were determined by an independent T-test, with Cohen’s effect size (d) applied to determine the magnitude of any differences observed. For all means-based testing, minimum significance was considered to be achieved when p < 0.05, with a 95% confidence interval (CI). The Cohen’s d values were considered with 0.2, 0.5, and 0.8 values demonstrating small, moderate, and large effect sizes, respectively.³⁷

Results

All the subjects successfully completed the assessments. Significant correlations between anthropometric and paddling variables in the cohort and COMP group are presented in Table 1. As mentioned previously, correlations between anthropometric, UE maximal strength, and paddling variables for REC surfers are not displayed due to a lack of relevance to the study’s aims.

Table 1.

Significant correlations (p < 0.05) between paddling, upper body strength, and anthropometric variables in competitive and recreational surfers.

	5 m	10 m	15 m	Pvel	400 m
Pooled
REL arm span	−0.46	−0.45	−0.45	0.46	−0.57**
Sum7 skinfolds	0.41	0.40	0.39	−0.42	0.48**
REL 1RM pull up	−0.43	−0.42	−0.41	0.42	−0.33*
COMP
Sum 7 skinfolds	0.71**	0.70**	0.68	−0.65	0.87**
Weight	0.70**	0.71**	0.70**	−0.67	0.75**
REL 1RM dip	−0.76**	−0.74**	−0.71**	0.66	−0.48*

Denotes significance at p > 0.05.

Denotes significance at p < 0.01.

Competitive surfers were significantly quicker in all aspects of paddling variables (Table 2 and Figures 1, 2, 3). Competitive surfers also had a significantly longer relative arm span than recreational counterparts. Comparisons of the differences between COMP and REC groups are presented in Table 2.

Figure 1.

Sprint paddle kinematics in competitive (n = 13) vs recreational (n = 16) surfers. 5 m (p0.05, d0.82), 10 m (p0.04, d0.87), 15 m (p0.04, d0.91).

Figure 2.

400 m time trial in competitive (n = 13) vs recreational (n = 16) surfers. 400 m (p0.01, d1.36).

Figure 3.

15 m paddle peak velocity and 400 m paddle average velocity in competitive (n = 13) vs recreational (n = 16) surfers. 15 m PVel (p0.02, d1.03), 400 m AVel (p0.00, d0.84).

Discussion

The purpose of this investigation was to assess the potential relationship between anthropometry, UE strength qualities (pull up and dip), and paddling kinematics in surfers and, in particular, COMP surfers. As the previous research⁸ in COMP surfers found a correlation between arm span and sprint paddle performance, this study seemed valuable to further explore the possible interactions between anthropometry and surfboard paddling. The relative arm span correlations with the paddling performance re-confirm some of the previous anthropometric research from swimming (in particular the freestyle stroke^14,15) and will also assist the talent identification programs in competitive surfing.

The high and very high positive correlations found between fat mass with paddling kinematics in COMP and moderate correlations in the whole cohort suggests that surfers (and especially COMP surfers) require low levels of fat mass to optimize their surfboard paddling performance. The high and very high correlations between mass and paddling kinematics in COMP surfers also indicates that there is a “threshold” weight for fat-free mass above which performance enhancements will be hampered. Even if the athlete is very lean, the increased weight appears likely to decrease their performance. The strongest association between fat mass and weight with paddling performance was with 400 m time trial (r = 0.87 and r = 0.75 respectively). Based on this and the notion that efficiency is paramount to increased performance in any repeated cyclical movement, excess fat mass or weight is likely to impede levels of prolonged surfboard paddling performance, especially in an environment where buoyancy and hydrodynamics are issues.

As found in the previous research,⁸ there was a significant moderate correlation between relative 1RM pull up strength and sprint paddling ability (5 m, 10 m, 15 m, and Pvel). However, there does not seem to be a significant correlation with 1RM pull up strength and endurance paddling (400 m) ability (r = −0.33, p = 0.08). This may be due to the fact that as with the initiation of any movement,³⁸ a surfer must overcome a higher resistance to begin with to accelerate their body and surfboard on the water. Therefore, it is logical considering the associations between acceleration and both upper and lower body strength, where correlations between upper body strength and paddling speed decrease as distance increases.^{8,17,21,39–42}

However, when the COMP cohort was examined, the significant correlation between relative 1RM pull up strength and sprint paddling ability did not exist. This is dissimilar to previous research although it should be noted that Sheppard et al.⁸ found differences in COMP surfers between faster and slower paddlers with relative 1RM pull up strength of 1.27 and 1.15, respectively. As the current average relative 1RM pull up strength for COMP surfers was 1.24, this may indicate that once a certain level of relative pull up strength is reached (e.g. above 1.2), improvements in paddling speed are not necessarily associated with pull up strength. Further improvements in paddling speed above this point may be associated with other exercises (e.g. dip strength as outlined below), CKC pulling exercises that focus on faster contraction speeds and higher stretch shortening cycle activity. Furthermore, the specific paddling-based interventions may be utilized to promote a positive effect. For example, sprint-interval paddle training methods, resisted paddling, or over-speed paddling (paddling with a current) are all worthy of evaluation.

Another noteworthy observation was that relative 1RM dip strength in COMP surfers was very highly correlated with the sprint paddling ability (p < 0.01). Similar to the relative 1RM pull up strength, this was not correlated with the endurance paddling ability. More research is needed on the pull up and dip in relation to the paddling ability; including if repetition maximum at bodyweight pull ups and dips are correlated to the paddling endurance performance.

As found in the previous researches,^6,8,11 sprint paddling kinematics (5 m, 10 m, 15 m, Pvel) were a valid discriminator between surfers of differing competitive levels. Our investigation also found a significant difference (p < 0.01) in the endurance paddling ability between surfers of different aptitude. This supports the aforementioned concept that paddling endurance in surfers may be better assessed with a water-based paddling time trial rather than in a lab-based setting^11,12 due to contextual validity and the nature of the kinetic chain (e.g. open vs. closed) assessed in the test. Our results also appear to indicate that REC surfers may improve surfing ability with a training focus towards improving paddling endurance over 400 m (rather than improving sprint paddle scores) as this is the largest difference between groups. Unlike paddling, it does not seem that the upper body strength is a valid measure to distinguish between surfers of different abilities.

Conclusion

The outcomes and performance data from this study will assist in the talent identification of surfers and also help with anthropometric monitoring of elite surfers during their competitive career. For dry land training, it will also direct strength and conditioning coaches (along with dieticians) to tailor individual surfer’s training and nutrition programs to ensure high levels of relative strength in pull up and dip are achieved, low levels of fat mass are maintained, and that any extra mass developed through training will not be of detriment to surfing performance. For water-based training, strength and conditioning coaches should also establish and maintain a high level of surfboard paddling endurance in both professional and recreational surfers.

Table 2.

Comparison of paddling, upper body strength, and anthropometric variables between competitive (n = 13) and recreational (n = 16) surfers.

	COMP	REC	p-value	d
5 m (s)	3.88 ± 0.40*	4.35 ± 0.75	0.04	−0.82
10 m (s)	6.86 ± 0.56*	7.64 ± 1.23	0.03	−0.87
15 m (s)	9.86 ± 0.74*	11.03 ± 1.85	0.03	−0.91
Pvel (m/s)	1.74 ± 0.10**	1.59 ± 0.18	0.01	1.03
400 m (s)	364.93 ± 42.69**	452.66 ± 86.38	0.00	−1.36
AvVel (m/s)	1.11 ± 0.12**	0.91 ± 0.12	0.00	0.84
REL pull	1.24 ± 0.13	1.29 ± 0.18	0.32	−0.35
REL dip	1.33 ± 0.14	1.48 ± 0.25*	0.03	−0.74
Weight (kg)	76.18 ± 8.71	76.98 ± 10.88	0.81	−0.08
Sum7 (mm)	88.56 ± 33.60	91.77 ± 40.50	0.82	0.09
LMI	1.00 ± 0.35	0.95 ± 0.43	0.74	0.13
Height (cm)	176.89 ± 5.50	177.72 ± 8.61	0.72	−0.12
REL height	0.51 ± 0.01	0.51 ± 0.01	0.46	0.29
REL arm span	1.04 ± 0.02**	1.02 ± 0.02	0.00	−1.16
REL biwidth	0.24 ± 0.03	0.22 ± 0.02	0.11	−0.67

Denotes significance at p < 0.05.

Denotes significance at p < 0.01.

Footnotes

Acknowledgements

This research was completed as a part of the collaboration between Surfing Australia and Edith Cowan University. Without the work of Surfing Australia staff including Dr Jeremy Sheppard and the staff at Coyne Sports Injury Clinic, this study would not have been able to be completed.

There are no people involved in the study where professional relationships will benefit from the results of the study.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

References

Meir

Lowdon

Davie

. Heart rates and estimated energy expenditure during recreational surfing. Aust J Sci Med Sport 1991; 20: 70–74.

Mendez-Villanueva

Bishop

Hamer

. Activity profile of world-class professional surfers during competition: A case study. J Strength Cond Res 2006; 20: 477–482.

Farley

Harris

Kilding

. Physiological demands of competitive surfing. J Strength Cond Res 2012; 26: 1887–1896.

Mendez-Villanueva

Bishop

. Physiological aspects of surfboard riding performance. Sports Med 2005; 35: 55–70.

Sheppard J. Activity profile of professional surfers using micro-sensors. In: Surfing Australia annual coaching conference, Gold Coast, Australia, 2011.

Loveless

Minahan

. Peak aerobic power and paddling efficiency in recreational and competitive junior male surfers. Eur J Sport Sci 2010; 10: 407–415.

Mendez-Villanueva

Perez-Landaluce

Bishop

. Upper body aerobic fitness comparison between two groups of competitive surferboard riders. J Sci Med Sport 2005; 8: 43–51.

Sheppard

McNamara

Osborne

. Association between anthropometry and upper-body strength qualities with sprint paddling performance in competitive surfers. J Strength Cond Res 2012; 26: 3345–3348.

Ellenbecker

Davies

. Closed kinetic chain exercise: A comprehensive guide to multiple joint exercises, 1st ed. Champaign, IL: Human Kinetics, 2001.

10.

Kibler

. Closed kinetic chain rehabilitation for sports injuries. Phys Med Rehabil Clin N Am 2000; 11: 369–384.

11.

Sheppard

Nimphius

Haff

. Development of a comprehensive performance testing protocol for competitive surfers. Int J Sports Physiol Perform 2013.

12.

Coyne

JOC

. Influence of anthropometric and upper body strength qualities on surfboard paddling kinematics, Perth, WA: Edith Cowan University, 2015.

13.

Bulgakova

Vorontsov

Fomichenko

. Improving the technical preparedness of young swimmers by using strength training. Sov Sports Rev 1990; 25: 102–104.

14.

Carter

JEL

. Physical structure of Olympic athletes: Part 1, The Montreal Olympic Games Anthropological Project, Basel: Karger, 1982.

15.

Carter

JEL

Ackland

. Kinanthropometry in aquatic sports, Champaign, IL: Human Kinetics, 1994.

16.

Baker

. Comparison of upper-body strength and power between professional and college-aged rugby league players. J Strength Cond Res 2001; 15: 30–35.

17.

Baker

Nance

. The relationship between running speed and measures of strength and power in professional rugby league players. J Strength Cond Res 1999; 13: 230–235.

18.

Cormie

McGuigan

Newton

. Influence of strength on magnitude and mechanisms of adaptation to power training. Med Sci Sports Exer 2010; 42: 1566–1581.

19.

Cormie

McGuigan

Newton

. Developing maximal neuromuscular power: Part 2 - Training considerations for improving maximal power production. Sports Med 2011; 41: 125–146.

20.

Cormie

McGuigan

Newton

. Developing maximal neuromuscular power: Part 1–Biological basis of maximal power production. Sports Med 2011; 41: 17–38.

21.

Donati

. The association between the development of strength and speed. New Stud Athletics 1996; 2: 51–58.

22.

Esteve-Lanao

Rhea

Fleck

. Running-specific, periodized strength training attenuates loss of stride length during intense endurance running. J Strength Cond Res 2008; 22: 1176–1183.

23.

Wisloff

Castagna

Helgerud

. Strong correlation of maximal strength with sprint performance and vertical jump height in elite soccer players. Br J Sports Med 2004; 38: 285–288.

24.

Hoff

Gran

Helgerud

. Maximal strength training improves aerobic endurance performance. Scand J Med Sci Sports 2002; 12: 288–295.

25.

Hoff

Helgerud

Wisloff

. Maximal strength training improves work economy in trained female cross-country skiers. Med Sci Sports Exer 1999; 31: 870–877.

26.

Storen

Helgerud

Stoa

. Maximal strength training improves running economy in distance runners. Med Sci Sports Exer 2008; 40: 1087–1092.

27.

Sunde

Storen

Bjerkaas

. Maximal strength training improves cycling economy in competitive cyclists. J Strength Cond Res 2010; 24: 2157–2165.

28.

Baker

. Comparison of upper-body strength and power between professional and college-aged rugby league players. J Strength Cond Res 2001; 15: 30–35.

29.

Baker

. Differences in strength and power among junior-high, senior-high, college-aged, and elite professional rugby league players. J Strength Cond Res 2002; 16: 581–585.

30.

Baker

Newton

. Discriminative analyses of various upper body tests in professional rugby-league players. Int J Sports Physiol Perform 2006; 1: 347–360.

31.

Peyer

Pivarnik

Eisenmann

. Physiological characteristics of National Collegiate Athletic Association Division I ice hockey players and their relation to game performance. J Strength Cond Res 2011; 25: 1183–1192.

32.

Sheppard

Chapman

Gough

. Twelve month training induced changes in elite international volleyball players. J Strength Cond Res 2009; 23: 2096–2101.

33.

Slater

Duthie

Pyne

. Validation of a skinfold based index for tracking proportional changes in lean mass. Br J Sports Med 2006; 40: 208–213.

34.

Coyne

JOC

Tran

Secomb

. Reliability of pull up & dip maximal strength tests. J Aust Strength Cond 2015; 23: 21–27.

35.

Coyne JOC and Sheppard JM. Assessing sprint paddle ability in competitive surfers. In: Australian Strength & Conditioning Association international conference on applied strength & conditioning, Gold Coast, Australia, 2011.

36.

Batterham

Hopkins

. Making meaningful inferences about magnitutdes. Int J Sports Physiol Perform 2006; 1: 50–57.

37.

Cohen

. Statistical power analysis for the behavioral sciences, 2nd ed. Hillsdale, NJ: L. Erlbaum Associates, 1988.

38.

Enoka

. Neuromechanics of human movement, Champaign, IL: Human Kinetics, 2000.

39.

Blazevich

. Resistance training for sprinters (part 1): Theoretical considerations. Strength Cond Coach 1997; 4: 9–12.

40.

Blazevich

. Resistance training for sprinters (part 2): Exercise suggestions. Strength Cond Coach 1997; 5: 5–10.

41.

Lockie

Murphy

Schultz

. The effects of different speed training protocols on sprint acceleration kinematics and muscle strength and power in field sport athletes. J Strength Cond Res 2012; 26: 1539–1550.

42.

Loturco

Artioli

Kobal

. Predicting punching acceleration from selected strength and power variables in elite karate athletes: A multiple regression analysis. J Strength Cond Res 2014; 28: 1826–1832.