Physical Game Demands of Ice Hockey Part 2: Strength, Power, Speed & Body Composition
In part 1 of this series, we discussed the importance of anaerobic and aerobic fitness capacities for ice hockey athletes whilst also defining the differences that exist in metabolic demands between forward and defensemen positional groups.
Today, we'll focus on the physiological and biomechanical characteristics of game play that requires the development and expression of strength, power, and speed.
Strength and Power For Hockey
The substantial force demands of ice hockey for events such as sprinting, collisions during body checking and dynamic exertions for puck battles demonstrate the importance of strength and power.
In particular, high percentages of maximal intensity muscle contraction have been identified during EMG analysis of the quadriceps and hamstrings during game simulated sprint skating (1). Isokinetic maximum force production has also been significantly associated with single bout on-ice speed (48-54 m) in collegiate male and adult female players (2,3). This reflects the significant force requirement for impulse generation needed during the acceleration phase of skating (1).
Strength has also been associated with successful game performance in men's National Collegiate Athletics Association (NCAA) division I ice hockey players over a full competitive season. Peyer et al. (4) found lower and upper body markers of strength significantly correlated (r = 0.554, r = 0.499) to a players plus/minus (+/-) score indicating that ice hockey performance is predicted by a player's total body strength capacity.
This study reported top players (determined by coach grouping) to be stronger in measures of bench press, chin ups and leg press versus bottom players. Hoff et al. (5) also found measures of strength to differentiate elite player status. This study reported greater muscle mass, strength (squat and bench press 1 repetition maximum [RM]) and peak force production during jumping in first team players vs. junior players (5). Consequently, junior athletes who are stronger and carry more muscle mass may have a greater potential to continue to play at the elite first team level.
Force Production
An athlete's ability to produce leg power has also been associated with on-ice physical performance. Early studies into the athletic demands of professional men's ice hockey identified vertical jump power to be a strong predictor (r = -0.85) of on-ice speed (54.9 m) (6). Vertical jump power has proven to be a consistent predictor of single bout acceleration and speed in collegiate male (7–9), collegiate female (9,10), junior male (11) and junior female (12) ice hockey players.
Farlinger et al. (8) reported significant correlations (p < 0.01) between on-ice sprints (30 m) and off-ice measures of leg power which included vertical jump (r = -0.71), broad jump (r = -0.74), wingate relative mean (r = -0.73) and peak power (-0.71) and wingate absolute mean power (r = -0.74), in 36 competitive players representing a diversity of playing levels. Although biomechanically different to skating, these dynamic measures reflect the underlying importance of power production for skating speed.
The limited research that has failed to identify an association between leg power and skating performance in ice hockey has assessed the speed component during flying sprint measurements (1). This may eliminate the acceleration phase and allow the athlete to generate momentum prior to the measurement of speed, thus reducing the role of strength and power. Like land-based sprinting, the generation of skating speed is partly dependent on utilizing the propulsive characteristics that determine stride length (13,14).
Optimal skating stride length is developed via powerful extension of the hip, knee and ankle during the push off phase to overcome inertia and develop acceleration (1,8). Given that ice hockey demands multiple accelerations and changes of direction with very little time spent at top skating speed (15), the ability to repeatedly develop leg extension power appears to be a critical physical requirement of the game.
While the association of leg power and game performance (e.g. +/- score, net scoring chances) has yet to be established, off-ice measures of anaerobic capacity have been used to provide information as to the future success of a payer. Burr et al. (16) analyzed physical performance data from 8 years (n = 853) of the National Hockey League Entry Draft (NHLED) and found peak anaerobic power, measured via a 30 second wingate test, was a significant variable in a multivariate model for predicting draft entry position. Burr et al. (17) also proposed the use of leg power rankings of elite junior players to predict the order of their selection during the 2005 NHLED.
This study found significant (p = 0.01) moderate correlations for countermovement jump performance and draft position (r = 0.42) and squat jump performance and draft position (r = 0.47). Burr et al. (17) concluded that squat jump accounted for 25% of the variance in draft selection order emphasizing the value placed on leg power as an indicator for determining the playing ability of an elite player.
In support of these findings, greater anaerobic power has been found to differentiate playing ability between collegiate athletes. Peterson et al. (18) found NCAA division I players scored significantly better in vertical jump (p = 0.001) and wingate peak power (p =0.05) than their division III counterparts. This study reported no significant differences in aerobic capacity between the two playing groups, leg power however proved to be an important marker that contributed to the physiological differences between the two levels of play.
Both strength and power are important physical characteristics that support ice hockey performance. These factors may be of greater importance as playing standard and competition demands increase. Lower body strength and power provide the foundation on which skating speed is maximized in conjunction with skating mechanics. The development of training programs that address both maximum force production (strength) and the rate of fore development (power) are therefore important considerations for optimizing ice hockey specific physical preparation.
Speed for Hockey
It has been demonstrated that sprinting comprises 11% of the total distance covered during an National Hockey League (NHL) game (15). This is a much higher proportion of in-game activity demand when compared to other team sports such as rugby union (19), soccer (20), and field hockey (21). It has also been demonstrated that average skating speed significantly diminishes in period 3 and overtime (-5-8%) when compared to periods 1 and 2, while distance covered in very fast and sprint skating speeds drops off significantly in period 3 versus period 1 in both forwards and defensemen positions (15,22,23). External load measurements of on-ice skating intensity (on-ice load ⋅min-1) during professional games have also been shown to significantly decrease between period 1-2 (-2.61 ± 0.74%, p = 0.008) and 1-3 (-3.22 ± 0.74%, p < 0.001) (24).
This suggests the ability to sustain skating speed or reduce the decline in speed during the latter half of a game may be a critical physical factor that supports game performance.
In support of the importance of speed development, it has been established that measures of off-ice acceleration represent the best predictors of on-ice skating performance. Bracko et al. (12) demonstrated off-ice 40-yard dash measures to be a strong predictor of both on-ice speed (up to 44 m) and anaerobic capacity (on-ice repeated sprint ability) in female ice hockey players. Off-ice measures of speed (between 30-40 yards) have consistently been identified as predictor variables for on-ice speed measures in high school, collegiate, and elite junior male ice hockey players (r = 0.51 to r = 0.78 p = < 0.05) (1,8). These results suggest that the ability to accelerate and run fast on dry land may support high skating speeds and work outputs on the ice. In particular, Farlinger et al. (8) reported the strongest predictors of on-ice 35 m sprint capacity were measures of off-ice 30 m sprint (r = 0.78) and a repeated 3-hop broad jump (r = -0.78). Whilst other measures of leg power were also related (e.g. vertical jump, wingate peak power), the two measures that required repeated force production applied in a horizontal vector demonstrated the closest relationship with on-ice speed.
The biomechanics of forward speed skating in ice hockey are defined by high-velocity diagonal pushes involving hip extension, abduction, and external rotation, as well as knee extension and ankle plantar flexion. During force translation, the stance leg maintains a position of hip flexion and slight adduction and internal rotation, as well as knee flexion and ankle dorsiflexion (25).
Within these movement strategies, clear mechanical differences in both the frontal and sagittal plane have been identified between faster versus slower skaters. Buckeridge et al. (26) reported faster skaters exhibit greater hip adduction angles at initial contact compared to slower skaters which enabled them to use greater ranges of motion (ROM) and hip abduction velocity during propulsion. This study also found faster skaters produce greater hip extension at toe-off as well as greater knee extension velocities. The greater hip ROM and extension velocity that characterize high performing skaters allow for greater hip and knee joint moments during propulsion thus increasing the power output of each stride (26).
Ground contact times during skating have been reported to remain constant during forward skating as distance and speed increases (e.g. average contact time 0.33 ± 0.05 s over 34.25 m) (27). The opportunity for prolonged and effective force application into the ice during the skate stride may therefore be greater when compared to land based running in which ground contact times have been shown to diminish as speed increases over 40 m running distances (e.g. maximum ground contact time 0.193 s, minimum ground contact time 0.094 s) (28). Whilst ground contact times remain constant during progressive skating strides, body positional differences exist as skating distance increases. In particular, the acceleration phase of skating is defined by greater hip extension ROM and ankle plantar flexion similar to land based running whilst steady state (gliding) requires greater hip abduction ROM (26).
The mechanical profile of forward skating therefore requires joint extension, plantar flexion and force generation during the stride contact phase. These characteristics demonstrate why off-ice tests of running acceleration and leg power via jumping protocols have consistently proven to be the best predictors of on-ice skating speed. Consequently, the development of specific off-ice training programs that improve hip and knee extension rates of force development through greater ROM with longer ground contact times may have transference to on-ice skating speed.
These may include modalities such as horizontal plyometrics, loaded jumping, resisted speed training and short distance sprints (e.g. less than 15 m). It must be noted however that ice hockey skating is a complex motor task and the transfer of off-ice fitness characteristics to on-ice skating performance may rely on the proficiency of the athletes skating motor program (12).
For more on Speed Training For Hockey, my colleague Kevin Neeld wrote a whole book on the subject.
Body Composition For Hockey
Body size and composition play an important role in team sports as the balance between body fat and muscle mass has an influence on speed, power and cardiovascular capacity (29). Consequently, the assessment of body composition in ice hockey has become a common off-ice monitoring tool as it is believed to have a predictive relationship with certain on-ice performance metrics. In particular, moderate correlations between percentage body fat and measures of on-ice skating speed (speed over 54 m and speed over 89 m with a change of direction) have been reported in NCAA Division I athletes, suggesting higher body fat percentages may lead to slower skating speeds (2).
Lower percentage body fat in conjunction with greater anaerobic capacity and on-ice speed characteristics have also been reported in NCAA division I versus division III collegiate athletes (18). Excess body fat may reduce skating speed by contributing to the mass that must be moved on the ice but not contributing to muscular force production. This is reflected by Newton's second law (a = F/m) which specifies that increases in fat mass (m) without an increase in muscle force (F) will reduce acceleration (a) (30).
The displacement of excessive fat mass also requires energy expenditure, which increases the cost of skating movements thus placing a greater relative stress on the cardiovascular system which may reduce time to fatigue (29). Body index measures, which include assessments of height, lean mass and muscular development, have also been proven to identify success in the NHLED. This suggests elite athletes who possess greater muscle development and lower body fat percentages have a greater physiological potential to be high draft selections and transition into the NHL (16). Ice hockey athletes should therefore look to attain optimal levels of lean mass development and minimize excessive body fat. These anthropometric characteristics will support better on-ice economy of skating movements as well as faster skating speeds.
Final Thoughts on The Physical Demands for Hockey
Ice hockey athletes are required to express both maximum strength and power primarily through extension of the lower body during the propulsive phase of skating. These qualities may become more important as the standard of gameplay increases suggesting higher competitive levels of ice hockey demand greater expressions of force and rates of force development. With the game demands of ice hockey comprising proportionally more sprinting activity than other team sports, developing training methods to improve skating speed should be a primary goal for athletes at all competitive levels. Strength and power training should form the foundation from which skating speed can be developed in conjunction with an efficient skating motor program. Finally, with the mechanical profile of on-ice acceleration reflective of off-ice acceleration, training for on-ice speed may be supported by land-based modalities such as plyometrics, resisted sprints and short sprints.
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