Enda F. Whyte

The influence of reduced hamstring length on patellofemoral joint stress during squatting in healthy male adults

Increased patellofemoral joint (PFJ) stress has been implicated in the development of PFJ pathologies. Previous studies have identified a relationship between reduced hamstring length and patellofemoral pain syndrome. Hamstring stretching is also recommended in the management thereof. However, the relationship between reduced hamstring length and PFJ stress has not been explored in vivo during activities that load the PFJ, such as squatting. The objective of this study was to determine if persons with reduced hamstring length demonstrate increased PFJ stress during squatting compared with individuals without reduced hamstring length. Eight participants with, and eight participants without, reduced hamstring length were assessed to determine their PFJ contact area using magnetic resonance imaging, and their PFJ reaction force during squatting using motion analysis. Data collected were entered into a biomechanical model to calculate medial, lateral and total PFJ stress. It was found that participants with reduced hamstring length had significantly greater total (393.39 Pa/kg vs. 213.01 Pa/kg) and lateral (311.23 Pa/kg vs. 142.55 Pa/kg) PFJ stress at 60 degrees knee flexion during squat descent and ascent (427.75 Pa/kg vs. 255.64 Pa/kg and 337.75 Pa/kg vs. 170.63 Pa/kg, respectively). This was due to significantly increased PFJ reaction force at 60 degrees knee flexion during squat descent (12.18 N/kg vs. 7.21 N/kg) and ascent (13.03 N/kg vs. 8.72 N/kg), and lower medial PFJ contact area at 60 degrees knee flexion (88 mm(2) vs. 160 mm(2)). The results of this study demonstrate a relationship between reduced hamstring length and increased PFJ stress during squatting due to increased PFJ reaction force and reduced medial PFJ contact area.

A High-Intensity, Intermittent Exercise Protocol and Dynamic Postural Control in Men and Women

CONTEXT Deficits in dynamic postural control predict lower limb injury. Differing fatiguing protocols negatively affect dynamic postural control. The effect of high-intensity, intermittent exercise on dynamic postural control has not been investigated. OBJECTIVE To investigate the effect of a high-intensity, intermittent exercise protocol (HIIP) on the dynamic postural control of men and women as measured by the Star Excursion Balance Test (SEBT). DESIGN Descriptive laboratory study. SETTING University gymnasium. PATIENTS OR OTHER PARTICIPANTS Twenty male (age = 20.83 ± 1.50 years, height = 179.24 ± 7.94 cm, mass = 77.67 ± 10.82 kg) and 20 female (age = 20.45 ± 1.34 years, height = 166.08 ± 5.83 cm, mass = 63.02 ± 6.67 kg) athletes. INTERVENTION(S) We recorded SEBT measurements at baseline, pre-HIIP, and post-HIIP. The HIIP consisted of 4 repetitions of 10-m forward sprinting with a 90° change of direction and then backward sprinting for 5 m, 2 repetitions of 2-legged jumping over 5 hurdles, 2 repetitions of high-knee side stepping over 5 hurdles, and 4 repetitions of lateral 5-m shuffles. Participants rested for 30 seconds before repeating the circuit until they reported a score of 18 on the Borg rating of perceived exertion scale. MAIN OUTCOME MEASURE(S) A mixed between- and within-subjects analysis of variance was conducted to assess time (pre-HIIP, post-HIIP) × sex interaction effects. Subsequent investigations assessed the main effect of time and sex on normalized maximal SEBT scores. We used intraclass correlation coefficients to determine the test-retest reliability of the SEBT and paired-samples t tests to assess the HIIP effect on circuit times. RESULTS We found a time × sex effect (F(8,69) = 3.5; P range, <.001-.04; η(2) range, 0.057-0.219), with women less negatively affected. We also noted a main effect for time, with worse normalized maximal SEBT scores postfatigue (F(8,69) = 22.39; P < .001; η(2) range, 0.324-0.695), and for sex, as women scored better in 7 SEBT directions (F(8,69) = 0.84; P range, <.001-008; η(2) range, 0.088-0.381). The intraclass correlation coefficients demonstrated high (0.77-0.99) test-retest repeatability. Paired-samples t tests demonstrated increases in circuit time post-HIIP (P < .001). CONCLUSIONS The HIIP-induced fatigue negatively affected normalized maximal SEBT scores. Women had better scores than men and were affected less negatively by HIIP-induced fatigue.

Epidemiology of injury in male adolescent Gaelic games

OBJECTIVES There is a lack of epidemiological research in adolescent Gaelic games, with previous research primarily focusing on elite adult males. This study aimed to prospectively capture the epidemiology of injury in male adolescent Gaelic games over one year. DESIGN Prospective cohort study. METHODS Two hundred and ninety two (15.7±0.8 years) male adolescent Gaelic footballers and hurlers took part in a one year prospective epidemiological study. Injuries were assessed weekly by a certified Athletic Rehabilitation Therapist and an injury was defined as any injury sustained during training or competition resulting in restricted performance or time lost from play. An injury report form was utilised to standardise injury information. RESULTS Match injuries were more frequent in Gaelic footballers (9.26 per 1000h) and hurlers (11.11 per 1000h) than training injuries (2.69 and 3.01 per 1000h, respectively). Over a quarter of injuries in adolescent Gaelic footballers (26.7%) and hurlers (26.5%) were overuse in nature. Recurrent injuries were also frequent, particularly in adolescent Gaelic footballers (47.3%). Lower limb injuries predominated (football 74.7%, hurling 58%), particularly in the knee (18.7%, 20.0%) and ankle (12.0%, 10.0%). Hamstring injuries were more frequent in footballers (13.3%), with lower back injuries more common in hurlers (22.0%). Minor injuries were common in hurling (61.7%), with moderate (20.8%) and severe (37.5%) injuries predominant in Gaelic football. CONCLUSIONS Injuries are frequent in adolescent Gaelic games and this study sets the scene for the establishment of injury prevention strategies for this at risk population.

Epidemiology of injury in male collegiate Gaelic footballers in one season.

Despite the popularity of collegiate Gaelic football in Ireland and the recent expansion into the United Kingdom and United States, no previous study has examined injury incidence. A prospective epidemiological study was implemented to establish injury incidence in 217 (19.3 ± 1.9 years) male collegiate Gaelic footballers from two collegiate institutions in one season. An injury was defined as any injury sustained during training or competition resulting in time lost from play or athlete reported restricted performance. Athletic therapy and training students, alongside a certified athletic and rehabilitation therapist, attended all training/matches over one season, and injuries were recorded using a standardized injury report form. The match injury rate was 25.1 injuries per 1000 h, with a significantly higher match injury rate noted in fresher players (players in their 1st year of higher education) (41.6 injuries per 1000 h) than senior players (12.7 injuries per 1000 h). Lower limb injuries were predominant (71.1%), particularly in the hamstring (15.5%), knee (14.1%), and ankle (11.3%). Soft‐tissue injuries predominated, particularly strains (32.4%) and sprains (27.5%). A scan and surgery was required in 31% and 12% of injuries, respectively. Thus, injuries are prevalent in male collegiate Gaelic football, and injury prevention programs are required.

The novel use of a SenseCam and accelerometer to validate training load and training information in a self-recall training diary

Abstract Self-recall training diaries are a frequently used tool to quantify training load and training information. While accelerometers are predominantly used to validate training diaries, they are unable to validate contextual training information. Thus this study aimed to examine the novel use of data fusion from a wearable camera device (SenseCam) and accelerometer to validate a self-recall training diary. Thirty participants filled in a training diary for 1 day while simultaneously wearing a SenseCam and accelerometer. The training diary was validated using Bland–Altman plots, Spearman’s rank-order correlation, percentage agreement and κ measure of agreement between the diary and the SenseCam and accelerometer. The results demonstrated overall agreement, and no bias, between the training diary and the accelerometer for training intensity, and the SenseCam for duration of activity and travel time. A positive correlation was found for duration (r = 0.82, P < 0.001) and intensity (r = 0.67, P < 0.001). Hundred per cent agreement was found between the SenseCam and training diary for activity, training surface and footwear (κ = 1, P < 0.0001), with a lower agreement noted for sports played (97.3%, κ = 0.91, P < 0.0001). The self-recall training diary was found to be a valid measure of capturing training load and training information using the combined wearable camera device and accelerometer.

The effect of a high intensity, intermittent exercise protocol on neurocognitive function in healthy adults: implications for return to play management following sport related concussion

CONTEXT Determination of return to play (RTP) after sport-related concussion (SRC) is critical given the potential consequences of premature RTP. Current RTP guidelines may not identify persistent exercise-induced neurocognitive deficits in asymptomatic athletes after SRC. Therefore, postexercise neurocognitive testing has been recommended to further inform RTP determination. To implement this recommendation, the effect of exercise on neurocognitive function in healthy athletes should be understood. OBJECTIVE To examine the acute effects of a high-intensity intermittent-exercise protocol (HIIP) on neurocognitive function assessed by the Symbol Digits Modality Test (SDMT) and Stroop Interference Test. DESIGN Cohort study. SETTING University laboratory. PARTICIPANTS 40 healthy male athletes (age 21.25 ± 1.29 y, education 16.95 ± 1.37 y). INTERVENTION Each participant completed the SDMT and Stroop Interference Test at baseline and after random allocation to a condition (HIIP vs control). A mixed between-within-subjects ANOVA assessed time- (pre- vs postcondition) -by-condition interaction effects. MAIN OUTCOME MEASURES SDMT and Stroop Interference Test scores. RESULTS There was a significant time-by-condition interaction effect (P < .001, η2 = .364) for the Stroop Interference Test scores, indicating that the HIIP group scored significantly lower (56.05 ± 9.34) postcondition than the control group (66.39 ± 19.6). There was no significant time-by-condition effect (P = .997, η2 < .001) for the SDMT, indicating that there was no difference between SDMT scores for the HIIP and control groups (59.95 ± 10.7 vs 58.56 ± 14.02). CONCLUSIONS In healthy athletes, the HIIP results in a reduction in neurocognitive function as assessed by the Stroop Interference Test, with no effect on function as assessed by the SDMT. Testing should also be considered after high-intensity exercise in determining RTP decisions for athletes after SRC in conjunction with the existing recommended RTP protocol. These results may provide an initial reference point for future research investigating the effects of an HIIP on the neurocognitive function of athletes recovering from SRC.

The effect of high intensity exercise and anticipation on trunk and lower limb biomechanics during a crossover cutting manoeuvre

ABSTRACT We investigated the effects of high intensity, intermittent exercise (HIIP) and anticipation on trunk, pelvic and lower limb biomechanics during a crossover cutting manoeuvre. Twenty-eight male, varsity athletes performed crossover cutting manoeuvres in anticipated and unanticipated conditions pre- and post-HIIP. Kinematic and kinetic variables were captured using a motion analysis system. Statistical parametric mapping (repeated-measures ANOVA) was used to identify differences in biomechanical patterns. Results demonstrated that both unanticipation and fatigue (HIIP) altered the biomechanics of the crossover cutting manoeuvre, whereas no interactions effects were observed. Unanticipation resulted in less trunk and pelvic side flexion in the direction of cut (d = 0.70 – 0.79). This led to increased hip abductor and external rotator moments and increased knee extensor and valgus moments with small effects (d = 0.24–0.42), potentially increasing ACL strain. The HIIP resulted in trivial to small effects only with a decrease in internal knee rotator and extensor moment and decreased knee power absorption (d = 0.35), reducing potential ACL strain. The effect of trunk and hip control exercises in unanticipated conditions on the crossover cutting manoeuvre should be investigated with a view to refining ACL injury prevention programmes.

Effects of a dynamic core stability program on the biomechanics of cutting maneuvers: A randomized controlled trial

Deficits in trunk control predict ACL injuries which frequently occur during high‐risk activities such as cutting. However, no existing trunk control/core stability program has been found to positively affect trunk kinematics during cutting activities. This study investigated the effectiveness of a 6‐week dynamic core stability program (DCS) on the biomechanics of anticipated and unanticipated side and crossover cutting maneuvers. Thirty‐one male, varsity footballers participated in this randomized controlled trial. Three‐dimensional trunk and lower limb biomechanics were captured in a motion analysis laboratory during the weight acceptance phase of anticipated and unanticipated side and crossover cutting maneuvers at baseline and 6‐week follow‐up. The DCS group performed a DCS program three times weekly for 6 weeks in a university rehabilitation room. Both the DCS and control groups concurrently completed their regular practice and match play. Statistical parametric mapping and repeated measures analysis of variance were used to determine any group (DCS vs control) by time (pre vs post) interactions. The DCS resulted in greater internal hip extensor (P=.017, η2=0.079), smaller internal knee valgus (P=.026, η2=0.076), and smaller internal knee external rotator moments (P=.041, η2=0.066) during anticipated side cutting compared with the control group. It also led to reduced posterior ground reaction forces for all cutting activities (P=.015‐.030, η2=0.074‐0.105). A 6‐week DCS program did not affect trunk kinematics, but it did reduce a small number of biomechanical risk factors for ACL injury, predominantly during anticipated side cutting. A DCS program could play a role in multimodal ACL injury prevention programs.

Is Poor Hamstring Flexibility A Risk Factor for Hamstring Injury in Gaelic Games

CONTEXT Hamstring injuries are a leading cause of injury in Gaelic games. Hamstring flexibility as a risk factor for hamstring injury has not yet been examined prospectively in Gaelic games. OBJECTIVE To examine whether hamstring flexibility, using the modified active knee extension (AKE) test, and previous injury are risk factors for hamstring injury in Gaelic players and to generate population-specific AKE cutoff points. DESIGN Prospective cohort study. SETTING School and colleges. Patients (or Other Participants): Adolescent and collegiate Gaelic footballers and hurlers (n = 570). INTERVENTION(S) The modified AKE test was completed at preseason, and hamstring injuries were assessed over the course of one season. Any previous hamstring injuries were noted in those who presented with a hamstring injury. MAIN OUTCOME MEASURES Bilateral AKE scores and between-leg asymmetries were recorded. Receiver operating characteristic curves were implemented to generate cutoff points specific to Gaelic players. Univariate and backward stepwise logistic regression analyses were completed to predict hamstring injuries, hamstring injuries on the dominant leg, and hamstring injuries on the nondominant leg. RESULTS Mean flexibility of 64.2° (12.3°) and 64.1° (12.4°) was noted on the dominant and nondominant leg, respectively. Receiver operating characteristic curves generated a cutoff point of < 65° in the AKE on the nondominant leg only. When controlled for age, AKE on the nondominant leg was the only predictor variable left in the multivariate model (odds ratio = 1.03) and significantly predicted hamstring injury (χ2 = 9.20, P = .01). However, the sensitivity was 0% and predicted the same amount of cases as the null model. It was not possible to generate a significant model for hamstring injuries on the dominant leg (P > .05), and no variables generated a P value < .20 in the univariate analysis on the nondominant leg. CONCLUSIONS Poor flexibility noted in the AKE test during preseason screening and previous injury were unable to predict those at risk of sustaining a hamstring strain in Gaelic games with adequate sensitivity.

The effects of limb dominance and a short term, high intensity exercise protocol on both landings of the vertical drop jump: implications for the vertical drop jump as a screening tool

Abstract The effectiveness of vertical drop jumps (VDJs) to screen for non-contact ACL injuries is unclear. This may be contributed to by discrete point analysis, which does not evaluate patterns of movement. Also, limited research exists on the second landing of VDJs, potential lower limb performance asymmetries and the effect of fatigue. Statistical parametric mapping investigated the main effects of landing, limb dominance and a high intensity, intermittent exercise protocol (HIIP) on VDJ biomechanics. Twenty-two male athletes (21.9 ± 1.1 years, 180.5 ± 5.5 cm, 79.4 ± 7.8 kg) performed VDJs pre- and post-HIIP. Repeated measures ANOVA identified pattern differences during the eccentric phases of the first and second landings bilaterally. The first landing displayed greater (internal) knee flexor (η2 = 0.165), external rotator (η2 = 0.113) and valgus (η2 = 0.126) moments and greater hip (η2 = 0.062) and knee (η2 = 0.080) flexion. The dominant limb generated greater knee flexor (η2 = 0.062), external rotator (η2 = 0.110) and valgus (η2 = 0.065) moments. The HIIP only had one effect, increased thoracic flexion relative to the pelvis (η2 = 0.088). Finally, the dominant limb demonstrated greater knee extensor moments during the second landing (η2 = 0.100). ACL injury risk factors were present in both landings of VDJs with the dominant limb at potentially greater injury risk. Therefore, VDJ screenings should analyse both landings bilaterally.