Contemporary Practices of Strength and Conditioning Coaches in High-Level Male Ice Hockey: A Survey-Based Investigation.

ABSTRACT: Galati, D, Turner, AN, Bishop, C, and Maloney, SJ. Contemporary practices of strength and conditioning coaches in high-level male ice hockey: a survey-based investigation. J Strength Cond Res 37(11): 2241-2250, 2023-The aim of this study was to provide an updated view of the common practices, ideologies, education level, and professional environment of strength and conditioning (S&C) coaches in elite male ice hockey. Nineteen S&C coaches from professional, semiprofessional, and top-tier collegiate hockey teams in North America completed an anonymous online survey. This was composed of 10 sections: (a) background information; (b) technology use, (c) testing and periodization, (d) strength and power, (e) flexibility/mobility, (f) speed, (g) plyometrics, (h) aerobic and anaerobic conditioning, (i) rehabilitation, and (j) challenges and areas of improvement. Fixed-response questions were analyzed through frequency analyses. Thematic analyses were used to identify common themes from open-response questions. Strength and conditioning coaches had an average of 8 (±6.5) years of experience when they accepted their current role. The majority held a master's degree and S&C certification. Muscular power, linear speed, and body composition were the most frequently tested qualities. Neuromuscular fatigue was the most important consideration during the season and least important consideration during the off-season. Training frequencies for all physical capacities were lower during the season compared with the off-season. All S&Cs had access to technology, with wearables, with force plates identified as the most used devices. This information may be used by S&C coaches to compare working practices with those used by their peers and inform them of the likely requirements and skill sets needed for job applications. Educational institutions may use this information to align teaching to current practice and to inform future research.

Acute and chronic effects of foam rolling vs eccentric exercise on ROM and force output of the plantar flexors.

Foam rolling and eccentric exercise interventions have been demonstrated to improve range of motion (ROM). However, these two modalities have not been directly compared. Twenty-three academy soccer players (age: 18 ± 1; height: 1.74 ± 0.08 m; body mass: 69.3 ± 7.5 kg) were randomly allocated to either a foam rolling (FR) or eccentric exercise intervention designed to improve dorsiflexion ROM. Participants performed the intervention daily for a duration of four weeks. Measurements of dorsiflexion ROM, isometric plantar flexion torque and drop jump reactive strength index were taken at baseline (pre-intervention) and at three subsequent time-points (30-min post, 24-hours post and 4-weeks post). A significant time x group interaction effect was observed for dorsiflexion (P = 0.036), but not for torque or reactive strength index. For dorsiflexion, there was a significant increase in both acute (30-min; P < 0.001) and chronic (4-week; P < 0.001) ROM for the eccentric group, whilst FR exhibited only an acute improvement (P < 0.001). Eccentric training would appear a more efficacious modality than foam rolling for improving dorsiflexion ROM in elite academy soccer players.

The Relationship Between Asymmetry and Athletic Performance: A Critical Review.

Maloney, SJ. The relationship between asymmetry and athletic performance: A critical review. J Strength Cond Res 33(9): 2579-2593, 2019-Symmetry may be defined as the quality to demonstrate an exact correspondence of size, shape, and form when split along a given axis. Although it has been widely asserted that the bilateral asymmetries are detrimental to athletic performance, research does not wholly support such an association. Moreover, the research rarely seeks to distinguish between different types of bilateral asymmetry. Fluctuating asymmetries describe bilateral differences in anthropometric attributes, such as nostril width and ear size, and are thought to represent the developmental stability of an organism. There is evidence to suggest that fluctuating asymmetries may be related to impaired athletic performance, although contradictory findings have been reported. Sporting asymmetries is a term that may better describe bilateral differences in parameters, such as force output or jump height. These asymmetries are likely to be a function of limb dominance and magnified by long-standing participation within sport. Sporting asymmetries do not seem to carry a clear influence on athletic performance measures. Given the vast discrepancy in the methodologies used by different investigations, further research is warranted. Recent investigations have demonstrated that training interventions can reduce sporting asymmetries and improve performance. However, studies have not sought to determine whether the influence of sporting asymmetry is independent of improvements in neuromuscular parameters. It may be hypothesized that the deficient (weaker) limb has a greater potential for adaptation in comparison to the strong limb and may demonstrate greater responsiveness to training.

Unilateral Stiffness Interventions Augment Vertical Stiffness and Change of Direction Speed.

Maloney, SJ, Richards, J, Jelly, L, and Fletcher, IM. Unilateral stiffness interventions augment vertical stiffness and change of direction speed. J Strength Cond Res 33(2): 372-379, 2019-It has previously been shown that preconditioning interventions can augment change of direction speed (CODS). However, the mechanistic nature of these augmentations has not been well considered. The current study sought to determine the effects of preconditioning interventions designed to augment vertical stiffness on CODS. Following familiarization, 10 healthy males (age: 22 ± 2 years; height: 1.78 ± 0.05 m; body mass: 75.1 ± 8.7 kg) performed 3 different stiffness interventions in a randomized and counterbalanced order. The interventions were: (a) bilateral-focused, (b) unilateral-focused, and (c) a control of CODS test practice. Vertical stiffness and joint stiffness were determined preintervention and postintervention using a single-leg drop jump task. Change of direction speed test performance was assessed postintervention using a double 90° cutting task. Performances following the unilateral intervention were significantly faster than control (1.7%; p = 0.011; d = -1.08), but not significantly faster than the bilateral intervention (1.0% faster; p = 0.14; d = -0.59). Versus control, vertical stiffness was 14% greater (p = 0.049; d = 0.39) following the unilateral intervention and 11% greater (p = 0.019; d = 0.31) following the bilateral intervention; there was no difference between unilateral and bilateral interventions (p = 0.94; d = -0.08). The findings of the current study suggest that unilateral preconditioning interventions designed to augment vertical stiffness improve CODS within this experimental cohort.

Postactivation Potentiation and Change of Direction Speed in Elite Academy Rugby Players.

Marshall, J, Turner, AN, Jarvis, PT, Maloney, SJ, Cree, JA, and Bishop, CJ. Postactivation potentiation and change of direction speed in elite academy rugby players. J Strength Cond Res 33(6): 1551-1556, 2019-This study investigated the effect of preceding proagility sprints with maximal isometric squats to determine if postactivation potentiation (PAP) could be harnessed in change of direction speed. Sixteen elite under-17 rugby union players (age: 16 ± 0.41 years; body mass: 88.7 ± 12.1 kg; height: 1.83 ± 0.07 m) from an Aviva Premiership rugby club were tested. Subjects performed a change of direction specific warm-up, followed by 2 baseline proagility tests. After 10-minute recovery, 3 × 3-second maximal isometric squats with a 2-minute recovery between sets were completed as a conditioning activity (CA) on a force plate where peak force and mean rate of force development over 300 milliseconds were measured. The proagility test was repeated at set time intervals of 1, 3, 5, and 7 minutes after the CA. Overall proagility times were significantly slower (p < 0.05) at 1 minute post-CA compared with the baseline (3.3%), with no significant differences occurring at 3, 5, or 7 minutes post-CA. Therefore, it appears that performing multiple sets of maximal isometric squats do not enhance proagility performance.

A Comparison of Bilateral and Unilateral Drop Jumping Tasks in the Assessment of Vertical Stiffness.

This study sought to compare vertical stiffness during bilateral and unilateral drop jumping. Specifically, the intersession reliabilities and force-deformation profiles associated with each task were to be examined. On 3 occasions, following familiarization, 14 healthy males (age: 22 [2] y; height: 1.77 [0.08] m; and body mass: 73.5 [8.0] kg) performed 3 bilateral, left leg and right leg drop jumps. All jumps were performed from a drop height of 0.18 m on to a dual force plate system. Vertical stiffness was calculated as the ratio of peak ground reaction force (GRF) to the peak center of mass (COM) displacement. Unilateral drop jumping was associated with higher GRF and greater COM displacement (both Ps < .001), but vertical stiffness was not different between tasks when considering individual limbs (P = .98). A coefficient of variation of 14.6% was observed for bilateral vertical stiffness during bilateral drop jumping; values of 6.7% and 7.6% were observed for left and right limb vertical stiffness during unilateral drop jumping. These findings suggest that unilateral drop jumps may exhibit greater reliability than bilateral drop jumps while eliciting similar vertical stiffness. It is also apparent that higher GRFs during unilateral drop jumping are mitigated by increased COM displacement.

Do stiffness and asymmetries predict change of direction performance?

Change of direction speed (CODS) underpins performance in a wide range of sports but little is known about how stiffness and asymmetries affect CODS. Eighteen healthy males performed unilateral drop jumps to determine vertical, ankle, knee and hip stiffness, and a CODS test to evaluate left and right leg cutting performance during which ground reaction force data were sampled. A step-wise regression analysis was performed to ascertain the determinants of CODS time. A two-variable regression model explained 63% (R2 = 0.63; P = 0.001) of CODS performance. The model included the mean vertical stiffness and jump height asymmetry determined during the drop jump. Faster athletes (n = 9) exhibited greater vertical stiffness (F = 12.40; P = 0.001) and less asymmetry in drop jump height (F = 6.02; P = 0.026) than slower athletes (n  = 9); effect sizes were both "large" in magnitude. Results suggest that overall vertical stiffness and drop jump height asymmetry are the strongest predictors of CODS in a healthy, non-athletic population.

A comparison of methods to determine bilateral asymmetries in vertical leg stiffness.

Whilst the measurement and quantification of vertical leg stiffness (Kvert) asymmetry is of important practical relevance to athletic performance, literature investigating bilateral asymmetry in Kvert is limited. Moreover, how the type of task used to assess Kvert may affect the expression of asymmetry has not been properly determined. Twelve healthy males performed three types of performance tasks on a dual force plate system to determine Kvert asymmetries; the tasks were (a) bilateral hopping, (b) bilateral drop jumping and (c) unilateral drop jumping. Across all the three methods, Kvert was significantly different between compliant and stiff limbs (P < 0.001) with a significant interaction effect between limb and method (P = 0.005). Differences in Kvert between compliant and stiff limbs were -5.3% (P < 0.001), -21.8% (P = 0.007) and -15.1% (P < 0.001) for the bilateral hopping, bilateral drop jumping and unilateral drop jumping methods, respectively. All the three methods were able to detect significant differences between compliant and stiff limbs, and could be used as a diagnostic tool to assess Kvert asymmetry. Drop jumping tasks detected larger Kvert asymmetries than hopping, suggesting that asymmetries may be expressed to a greater extent in acyclic, maximal performance tasks.

Effects of Concurrent Activation Potentiation on Countermovement Jump Performance.

The purpose of this study was to assess the effects of concurrent activation potentiation (CAP) on countermovement jump (CMJ) performance. Twenty-four resistance-trained males (mean ± SD; age: 25 ± 4 years, body mass: 78.7 ± 10.3 kg) performed a CMJ on a force plate under 4 different conditions: (a) a control condition where the CMJ was performed with hands on hips and lips pursed, thus preventing jaw or fist contraction from occurring, (b) a jaw condition where the CMJ was performed with maximal contraction of the jaw, (c) a fist condition where the CMJ was performed with maximal contraction of the fists, and (d) a combined condition where the CMJ was performed with maximal contraction of both jaw and fists. Jump height (JH), peak force (PF), rate of force development (RFD), and time to peak force (TTPF) were calculated from the vertical force trace. There was no significant difference in PF (p = 0.88), TTPF (p = 0.96), JH (p = 0.45), or RFD (p = 0.06) between the 4 conditions. Effect size (ES) comparisons suggest a potential for CMJ with fist and jaw contraction (BOTH condition) to augment both PF (2.4%; ES: 0.62) and RFD (9.9%; ES: 0.94) over a normal CMJ (NORM condition). It is concluded that CAP by singular and combined contractions has no significant impact on CMJ performance; however, substantial interindividual variation in response to CAP was observed, and such techniques may therefore warrant consideration on an individual basis.

Reliability of Unilateral Vertical Leg Stiffness Measures Assessed During Bilateral Hopping.

The assessment of vertical leg stiffness is an important consideration given its relationship to performance. Vertical stiffness is most commonly assessed during a bilateral hopping task. The current study sought to determine the intersession reliability, quantified by the coefficient of variation, of vertical stiffness during bilateral hopping when assessed for the left and right limbs independently, which had not been previously investigated. On 4 separate occasions, 10 healthy males performed 30 unshod bilateral hops on a dual force plate system with data recorded independently for the left and right limbs. Vertical stiffness was calculated as the ratio of peak ground reaction force to the peak negative displacement of the center of mass during each hop and was averaged over the sixth through tenth hops. For vertical stiffness, average coefficients of variation of 15.3% and 14.3% were observed for the left and right limbs, respectively. An average coefficient of variation of 14.7% was observed for bilateral vertical stiffness. The current study reports that calculations of unilateral vertical stiffness demonstrate reliability comparable to bilateral calculations. Determining unilateral vertical stiffness values and relative discrepancies may allow a coach to build a more complete stiffness profile of an individual athlete and better inform the training process.

Acute effects of a loaded warm-up protocol on change of direction speed in professional badminton players.

It has previously been shown that a loaded warm-up may improve power performances. We examined the acute effects of loaded dynamic warm-up on change of direction speed (CODS), which had not been previously investigated. Eight elite badminton players participated in three sessions during which they performed vertical countermovement jump and CODS tests before and after undertaking the dynamic warm-up. The three warm-up conditions involved wearing a weighted vest (a) equivalent to 5% body mass, (b) equivalent to 10% body mass, and (c) a control where a weighted vest was not worn. Vertical jump and CODS performances were then tested at 15 seconds and 2, 4, and 6 minutes post warm-up. Vertical jump and CODS significantly improved following all warm-up conditions (P < .05). Post warm-up vertical jump performance was not different between conditions (P = .430). Post warm-up CODS was significantly faster following the 5% (P = .02) and 10% (P < .001) loaded conditions compared with the control condition. In addition, peak CODS test performances, independent of recovery time, were faster than the control condition following the 10% loaded condition (P = .012). In conclusion, the current study demonstrates that a loaded warm-up augmented CODS, but not vertical jump performance, in elite badminton players.

The relationship between vertical stiffness during bilateral and unilateral hopping tests performed with different strategies and vertical jump performances.

Vertical stiffness has been highlighted as a potential determinant of performance and may be estimated across a range of different performance tasks. The aim of the current study was to investigate the relationship between vertical stiffness determined during 9 different hopping tests and performance of vertical jumps. Twenty healthy, active males performed vertical hopping tests with three different strategies (self-selected, maximal, and controlled) and three different limb configurations (bilateral, unilateral preferred, and unilateral non-preferred), resulting in nine different variations, during which vertical stiffness was determined. In addition, participants performed squat jump (SQJ) and countermovement jump (CMJ) during which jump height, CMJ stiffness, and eccentric utilization ratio (EUR) were determined. Vertical stiffness in bilateral and unilateral preferred tasks performed with a self-selected and maximal, but not controlled, strategy was associated with stiffness in the CMJ (r = 0.61-0.64; p < 0.05). However, stiffness obtained during unilateral preferred and non-preferred hopping with self-selected strategy was negatively associated with performance in SQJ and CMJ tasks (r = -0.50 to -0.57; p < 0.05). These findings suggest that high levels of vertical stiffness may be disadvantageous to static vertical jumping performance. In addition, unilateral hopping with a self-selected strategy may be the most appropriate task variation if seeking to determine relationships with vertical jumping performance.Highlights Stiffness obtained during unilateral hopping with a preferred strategy was negatively associated with vertical jumping performancesStiffness obtained during hopping with preferred and maximal strategies was associated with stiffness obtained during a countermovement jumpIn this population, hopping stiffness may therefore be reflective of an individual's countermovement jump strategyHigh levels of stiffness may be disadvantageous to static-start vertical jumping.

Lower limb stiffness testing in athletic performance: a critical review.

Stiffness describes the resistance of a body to deformation. In regard to athletic performance, a stiffer leg-spring would be expected to augment performance by increasing utilisation of elastic energy. Two-dimensional spring-mass and torsional spring models can be applied to model whole-body (vertical and/or leg stiffness) and joint stiffness. Various tasks have been used to characterise stiffness, including hopping, gait, jumping, sledge ergometry and change of direction tasks. Appropriate levels of reliability have been reported in most tasks, although they vary between investigations. Vertical stiffness has demonstrated the strongest reliability across tasks and may be more sensitive to changes in high-velocity running performance than leg stiffness. Joint stiffness demonstrates the weakest reliability, with ankle stiffness more reliable than knee stiffness. Determination of stiffness has typically necessitated force plate analyses; however, validated field-based equations permit determination of whole-body stiffness without force plates. Vertical, leg and joint stiffness measures have all demonstrated relationships with performance measures. Greater stiffness is typically demonstrated with increasing intensity (i.e., running velocity or hopping frequency). Greater stiffness is observed in athletes regularly subjecting the limb to high ground reaction forces (i.e., sprinters). Careful consideration should be given to the most appropriate assessment of stiffness on a team/individual basis.

Does a Loaded Warm-Up Influence Jump Asymmetry and Badminton-Specific Change of Direction Performance?

PURPOSE: Previously, it has been shown that loaded warm-up (LWU) can improve change-of-direction speed (CODS) in professional badminton players. However, the effect of asymmetry on CODS in badminton players and the influence of LWU on asymmetry has not been examined. METHODS: A total of 21 amateur badminton players (age 29.5 [8.4] y, playing experience 8.4 [4.2] y) completed 2 trials. In the first, they performed a control warm-up. In the second, they performed the same warm-up but with 3 exercises loaded with a weight vest (LWU). Following both warm-ups, players completed single-leg countermovement jump and badminton-specific CODS tests. RESULTS: No significant differences between control warm-up and LWU were observed for CODS, single-leg countermovement jump, or single-leg countermovement jump asymmetry. However, small effect sizes suggested faster CODS (mean difference: -5%; d = -0.32) and lower asymmetries (mean difference: -3%; d = -0.39) following LWU. Five players (24%) experienced CODS improvements greater than the minimum detectable change while 2 (10%) responded negatively. Asymmetry was not correlated with CODS following control warm-up (ρ = .079; P = .733) but was negatively associated with CODS after LWU (ρ = -.491; P = .035). CONCLUSION: LWU may prove a strategy to trial on an individual basis, but generic recommendations should not be applied.

Train the Engine or the Brakes? Influence of Momentum on the Change of Direction Deficit.

PURPOSE: Currently, it is unclear which physical characteristics may underpin the change of direction deficit (COD-D). This investigation sought to determine if momentum, speed-, and jump-based measures may explain variance in COD-D. METHODS: Seventeen males from a professional soccer academy (age, 16.76 [0.75] y; height, 1.80 [0.06] m; body mass, 72.38 [9.57] kg) performed 505 tests on both legs, a 40-m sprint, and single-leg countermovement and drop jumps. RESULTS: The regression analyses did not reveal any significant predictors for COD-D on either leg. "Large" relationships were reported between the COD-D and 505 time on both limbs (r = .65 to .69; P < .01), but COD-D was not associated with linear momentum, speed-, or jump-based performances. When the cohort was median split by COD-D, the effect sizes suggested that the subgroup with the smaller COD-D was 5% faster in the 505 test (d = -1.24; P < .001) but 4% slower over 0-10 m (d = 0.79; P = .33) and carried 11% less momentum (d = -0.81; P = .17). CONCLUSION: Individual variance in COD-D may not be explained by speed- and jump-based performance measures within academy soccer players. However, when grouping athletes by COD-D, faster athletes with greater momentum are likely to display a larger COD-D. It may, therefore, be prudent to recommend more eccentric-biased or technically focused COD training in such athletes and for coaches to view the COD action as a specific skill that may not be represented by performance time in a COD test.

Ballistic exercise as a pre-activation stimulus: a review of the literature and practical applications.

Post-activation potentiation (PAP) refers to the acute enhancement of muscular function as a direct result of its contractile history. Protocols designed to elicit PAP have commonly employed heavy resistance exercise (HRE) as the pre-activation stimulus; however, a growing body of research suggests that low-load ballistic exercises (BE) may also provide an effective stimulus. The ability to elicit PAP without the need for heavy equipment would make it easier to utilise prior to competition. It is hypothesised that BE can induce PAP given the high recruitment of type II muscle fibres associated with its performance. The literature has reported augmentations in power performance typically ranging from 2 to 5 %. The performance effects of BE are modulated by loading, recovery and physical characteristics. Jumps performed with an additional loading, such as depth jumps or weighted jumps, appear to be the most effective activities for inducing PAP. Whilst the impact of recovery duration on subsequent performance requires further research, durations of 1-6 min have been prescribed successfully in multiple instances. The effect of strength and sex on the PAP response to BE is not yet clear. Direct comparisons of BE and HRE, to date, suggest a tendency for HRE protocols to be more effective; future research should consider that these strategies must be optimised in different ways. The role of acute augmentations in lower limb stiffness is proposed as an additional mechanism that may further explain the PAP response following BE. In summary, BE demonstrates the potential to enhance performance in power tasks such as jumps and sprints. This review provides the reader with some practical recommendations for the application of BE as a pre-activation stimulus.