The Examination of Ice Hockey Forward and Backward Skating Mechanics

Ice hockey is a popular winter sport, and one of the most important skills in ice hockey is skating. Forward and backward skating may appear to be similar, but the body joint movements may be substantially different. The mechanics of backward skating is not well understood in comparison to the forward skating. Therefore, the purpose of this study was to examine the kinematic differences between forward and backward skating. Seven male collegiate ice hockey players participated in the study, and they skated both forward and backward (C-cut) four times each on the ice at their highest intensity from one end of the goal line to the other end of the goal line on the ice. A standard two-dimensional kinematic analysis was conducted to examine the lower body extremity and trunk at the instants of weight acceptance and propulsion. No significant differences in the joint angles were found at the weight acceptance. At propul -sion, significant differences were found in the joint angles of hip, knee, ankle and trunk between forward and backward skating. Additionally, the hip angular velocity was significantly different in both the weight acceptance and the propulsion phases. Hence, these findings indicate the importance of understanding mechanical difference between forward and backward skating for developing coaching instruction and prescribe strength and conditioning programs. Future studies are warranted to examine the mechanics of forward and backward skating using a 3D analysis and also on different positional players.


Introduction
Ice hockey is a popular sport in North America and Europe, and in 2019 there were approximately 567,900 registered ice hockey players in the United States [1]. Hockey is a fast paced sport requiring the ability to perform lower intensity striding and gliding, interspersed with bursts of high intensity skating. Other major skills performed in hockey include body checking, stick handling, passing and shooting. Many professional coaches, general managers, and scouts have long considered skating as the most important skill of all [2]. From a biomechanical perspective, having fundamental skating mechanics can contribute to fast skating and reduce head and lower body joint injury. Both Marino & Weese [3], and Pearsall, et al. [4] conducted a kinematic analysis of forward ice skating in hockey. These studies described the ice skating stride as consisting of three functional phases: 1) glide during single support, 2) propulsion during single support, and 3) propulsion during double support. The glide during single support phase coincides with the full extension of the propulsion leg, and the beginning of recovery of the leg back to the support position. The propulsion during the single support phase consists of drawing back the recovery leg while the leg that has been gliding and supporting the body externally rotates at the ankle and begins to push out and back. Finally, the propulsion during double support phase occurs once the recovery leg again contacts the ice under the body, and the propulsion continues with the other leg. This pattern is repeated as forward motion continues. The percentage of time in each stage differs across individuals and will also vary with speed and direction changes. Forward acceleration will continue as long as propulsion continues. Therefore, maintenance of speed is highly related to maximizing the amount of propulsion and minimizing the amount of glide.
The kinematics of forward ice skating have been well examined in the previous literature [4][5][6][7]. However, the kinematics of backward ice skating is not well understood because thus players participated in the study, and the authors found that the backward skating cycle time was 0.86 seconds with a cycle length of 5.65m. The authors also indicated that the backward skating velocity was 6.57m/s, which is approximately 81% of the forward skating velocity at 8.03m/s. Since in this study the camera was suspended from the overhead, the body mechanics of backward skating were not examined. Understanding the body mechanics of backward skating is crucial because it enables players to have proper balance on the ice while skating backward efficiently without falling, which potentially may cause serious head (i.e. concussion) and body joint injuries. Backward skating skill is also particularly important for defensive players in ice hockey. Twist & Rhodes [9] reported that defensive players play close to 50% of a game whereas forward players play approximately 35% of ice time. Hence, a defensive player spends a substantial amount of time on the ice skating backwards during a game. The mechanics of forward and backward skating can be similar but yet substantially different due to the direction of the skating motion. The researcher hypothesized that the players may have a greater lower extremity joint angles in forward skating than backward skating, so the skaters could propel themselves to skate faster with a higher velocity in forward skating than in backward skating. However, due to the lack of empirical evidence on backward skating mechanics, this observation needed to be examined and validated. Therefore, the purpose of this study was to examine and compare both kinematics of forward and backward ice skating in the lower extremity. The results would enable coaches to provide a comprehensive skating instruction for developing minor hockey players and beginners, and also trainers can prescribe a better strength and conditioning program to reduce body joint injury.

Participants and Experimental Design
Seven division II male intercollegiate club hockey players (mean age: 20.6 ± 2.6 years old; height: 1.8 ± 6.6m; mass: 82.9 ± 15.7kg) who were free of injury were recruited to participate in the study, and the Institutional Research Board (IRB) approved the study. Written informed consent was obtained from the participants prior to the study. Data collection took place at a local ice arena. Participants were asked to dress in dark, tight-fitting clothing, and to perform their usual off-ice warm up prior to arriving for testing. Upon A paired samples t-test with α = 0.05 was conducted using SPSS (v. 28) software to examine significant differences between forward and backward skating for the body joint kinematic variables.     .001* *Statistical significant at p < 0.05

Discussion and Implications
The motion between forward and backward skating may be

Conclusion
This research study compared the kinematics of forward and backward skating for male varsity ice hockey players. The results showed that the skaters demonstrated significantly greater hip, knee, and ankle extension movements at propulsion in forward skating than backward skating. Additionally, the skaters showed greater forward trunk lean in forward skating than in backward skating which may maximize their skating velocity. These findings indicate the importance of understanding the proper mechanics of skating for both forward and backward skating skills for developing coaching instruction. Further, these enable practitioners to prescribe strength and conditioning programs that match lower body joint action for both forward and backward skating skills.
Future studies are warranted to conduct a three-dimensional analysis in both forward and backward skating with different positional players.