This study investigated peak impact and push-off reaction forces during skating in sledge hockey to understand stresses on load-bearing limbs and predict potential overuse injuries. Five able-bodied male athletes propelled themselves off-ice using a sledge and motion capture was used to measure ground reaction forces. Results showed impacts of 1.2-3.1 times body weight created stresses on each arm for initiation, while push-offs generated 0.3-0.4 times body weight. Impacts posed greater injury risk than push-offs, with potential for shoulder and muscle soreness. Proper mechanics, weight training and care were recommended to protect shoulders.

1. Investigation of the relationship between peak impact and push-off reaction
forces, and potential upper-limb overuse/overloading injuries introduced from
skating in the sport of sledge hockey
A.M. Gal, A.D.C. Chan, and D.C. Hay
Increased stresses onto load-bearing joints can potentially produce overuse/overloading
injuries [1], [2]. Elevated stresses caused from weight-bearing motion potentially introduce
increased risk for these styles of injuries [1]–[3]. Shoulder dependent populations are at
heightened risk for overuse/overloading injuries involving the shoulders and upper limbs
[4], [5]. Sledge hockey is a high velocity, high impact, repetitive poling para-sport. Sledge
hockey has become popular establishing the need to investigate the sport’s most basic
skillset, skating. Skating is a cyclical double poling motion similar to cross-country skiing,
which consists of a contact (propulsion) and swing phase. The swing phase is divided into
two phases: 1) recovery, and 2) preparation. By investigating stick contact forces during
propulsion, a heightened understanding of the stresses introduced onto the load-bearing
limbs can be made. From this, potential injuries can then be predicted and preventative
measures prescribed. The objective of this study was to identify peak impact and push-off
reaction forces from skating in sledge hockey off-ice. Interpretations of the results were
based upon analogous previous researches regarding weight-bearing stress onto loading-
bearing joints [1]–[3], [6]–[8]. Predictions of overuse/overloading injuries potentially
caused from impact and push-off were provided.
Five adult male able-bodied athletes propelled themselves in a study-specific indoor, off-ice
sledge (two wheels per youth sized chassis replaced the blades, and a front wheel) through
a Vicon motion capture system equipped with five bilateral upper torso/limb BTS-wireless
surface electromyography (sEMG) electrodes [5], [6]; sEMG were not analyzed for this
study. Participants were sledge hockey and poling sport naïve; asymmetrical bilateral
skating was predicted. Left, right, and sledge-body ground reaction forces were acquired in
a study-specific 4-force plate design [7], [8]. Three useable trials (good force plate contact)
were collected per i) submaximal, and ii) maximal effort test for both the 1) SC, and 2) MC.
Two participants performed an additional MC maximal effort test adding variation to the
protocol. Data were processed offline using MATLAB [10]. A low pass zero-lag 2nd order
Butterworth filter (12 Hz) was applied to motion capture raw signals.
Results indicated that naïve sledge hockey players created between 1.2 and 3.1 times body
weight of stresses per arm, in order to initiate skating off-ice. At push-off, stresses
produced from each arm ranged between 0.3 and 0.4 times body weight. Aggregated
results suggested that potential injury is more likely to be caused from initial impact than
at push-off for a sledge hockey player. Potential upper body/limb injuries are predicted to
be acutely and chronically related to joint and/or muscle soreness, specifically concerning
the shoulder(s). Major concerns regarding causes for potential injury are suggested to
include: 1) the quick, forceful, and powerful elevated impacts, 2) body-weight stresses
involved with the point of rotation during motion production (shoulder), and 3) the
forceful extension completing force transfer producing forward displacement. From this,
heightened structural competence of the shoulder and upper limbs are encouraged through

2. improved stroke mechanics, weight training, and musculoskeletal care for shoulder
dependent populations. By increasing the awareness of potential injuries athletic careers
may be prolonged.
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