Browsing by Author "Jordan, Matthew J"

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    Injury Prevention in Youth Tackle Football
    (2023-09-22) Cairns, Joshua Thomas; Emery, Carolyn Ann; Schneider, Kathryn J; Jordan, Matthew J; Pasanen, Kati; Smith, Julianne D
    This thesis contains two projects that aim to investigate injury and injury prevention strategies in Canadian adolescent tackle football. The first project aimed to examine the current utilization of Neuromuscular Training components (NMT) in tackle football warm-ups and the second project examined adolescent (ages 14-17) tackle football epidemiology. Objectives: 1. To describe the current time spent by adolescent tackle football teams in five key neuromuscular training (NMT) components (aerobic, agility, balance and coordination, strength, and head on neck control) and determine if time in warm-up components differed throughout the season. 2. To describe injury rates, burden, types, mechanisms, and risk factors in adolescent (ages 14-17) community tackle football players in one season. Methods: Teams consented to video-recording of practice and game warm-ups. Video was analyzed using Dartfish tagging software (Dartfish, USA). Validated injury surveillance methods were used during a prospective cohort in a single nine-week competition season for participants aged 14-17. Injury rates (IR), concussion rates (CR), and incidence rate ratios (IRR) were reported based on univariable Poisson regression analyses (offset by player-hours and controlling for cluster by team). Results: Teams spent a median of 456.2 seconds in warm-up prior to sessions and a median time of 275 seconds in active warm-up components. Teams spent more time in some NMT components (aerobic and strength) compared to others (balance, agility and coordination, and head on neck control), however other than aerobic (58%) the use of other NMT components was low (time in NMT components 1-9%). Teams were relatively consistent with component utilization throughout the season. The overall IR was 4.61 injuries/1000 player-hours (95%CI; 3.84 – 5.53) and the CR was 1.20 concussions/1000 player-hours (95%CI; 0.90-1.61). Concussion rates were higher in games (IR=3.86 concussions/1000 player game-hours 95%CI; 2.74 – 5.43) than practices (IR=0.44 concussions/1000 practice player hours, 95%CI;0.25 – 0.75) (IRR=8.82,95%CI; 4.52- 18.27). Previous history of injury in the past 12 months (IRR=1.66,95%CI; 1.07-2.57) and being obese (BMI > 30.00) (IRR=2.55, 95%CI; 1.35-4.84) were associated with higher rates of practice-related injury. Lifetime history of concussion (IRR=1.58, 95%CI; 1.00 – 2.50) and being in the 75th percentile for height (IRR=1.58, 95%CI; 1.19 – 2.18) were associated with higher game-related injury rates, with the former being insignificant and the latter significant. Conclusions: Injury and concussion rates are high in adolescent tackle football. There are opportunities for research examining injury and concussion prevention strategies in tackle football in Canada. Football teams do not engage in NMT warm-up components and there is significant opportunity for implementation of such a prevention strategy in this sport.
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    Neuromuscular Function and Performance in Alpine Ski Racers with Anterior Cruciate Ligament Reconstruction: A Return to Sport Framework
    (2017) Jordan, Matthew J; Herzog, Walter; Aagaard, Per; Heard, Mark; Doyle-Baker, Patricia; Kolb, Jon; Holmberg, Hans-Christer; Edwards, Brent
    The primary aim of this study was to evaluate the effects of ACL injury on neuromuscular function in elite alpine ski racers, and to monitor skiers throughout the return to sport transition. In Chapter 2 a narrative review of the literature was performed on ACL injury, ACL re-injury, and return to sport after ACL injury in ski racing. In Chapter 3, a new test of inter-limb functional asymmetry was used to evaluate alpine ski racers with/without ACL reconstruction (ACLR). Despite a full return to competition, ACLR ski racers demonstrated elevated inter-limb functional asymmetries that were correlated with lower limb muscle mass asymmetry. In Chapter 4, hamstring/quadriceps strength ratios were measured in ski racers with/without ACLR. ACLR ski racers displayed significant hamstring/quadriceps strength deficits in the ACLR limb compared to the contralateral limb and the limb average of non-injured skiers. In Chapter 5, the functional lower-limb asymmetry test introduced in Chapter 3 was used to evaluate the acute effects of a fatiguing jump protocol on asymmetry and hamstring/quadriceps muscle activity in ski racers with/without ACLR. The ACLR skiers displayed systematic inter-limb functional asymmetries. ACLR skiers displayed reduced quadriceps muscle activity at takeoff in the surgical limb. Both the ACLR group and non-injured controls became quadriceps dominant with fatigue. Quadriceps muscle activity increased while hamstring muscle activity decreased. Notably, this was found in the pre-landing phase. In Chapter 6, primary ACLR operative reports from 28 skiers were analyzed to evaluate the associated pathology including multi-ligament injury, meniscal tears and chondral lesions. Operative reports from future surgeries were analyzed to evaluate the injury progression. At the time of primary ACLR, there was a higher proportion of chondral lesions in the lateral compartment compared to the medial compartment, and complex meniscal tears compared to one-dimensional tears. At the time point of future surgery, a significant proportion of skiers showed a worsening of chondral lesions, including half of the skiers presenting with Grade 3 or Grade 4 lesions. Functional asymmetry was also evaluated at various time points following primary ACLR. Nearly two years were required for functional asymmetry indices to reach values comparable to those of non-injured ski racers.