The effectiveness of vertical drop jumps (VDJs) to screen for non-contact ACL injuries is unclear... more 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 (η(2) = 0.165), external rotator (η(2) = 0.113) and valgus (η(2) = 0.126) moments and greater hip (η(2) = 0.062) and knee (η(2) = 0.080) flexion. The dominant limb generated greater knee flexor (η(2) = 0.062), external rotator (η(2) = 0.110) and valgus (η(2) = 0.065) moments. The HIIP only had one effect, increased thoracic flexion relative to the pelvis (η(2) = 0.088). Finally, the dominant limb demonstrated greater knee extensor moments during the second landing (η(2) = 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.
Exercise-based cardiac rehabilitation (CR) independently alters the clinical course of cardiovasc... more Exercise-based cardiac rehabilitation (CR) independently alters the clinical course of cardiovascular diseases resulting in a significant reduction in all-cause and cardiac mortality. However, only 15%-30% of all eligible patients participate in a phase 2 ambulatory programme. The uptake rate of community-based programmes following phase 2 CR and adherence to long-term exercise is extremely poor. Newer care models, involving telerehabilitation programmes that are delivered remotely, show considerable promise for increasing adherence. In this view, the PATHway (Physical Activity Towards Health) platform was developed and now needs to be evaluated in terms of its feasibility and clinical efficacy. In a multicentre randomised controlled pilot trial, 120 participants (m/f, age 40-80 years) completing a phase 2 ambulatory CR programme will be randomised on a 1:1 basis to PATHway or usual care. PATHway involves a comprehensive, internet-enabled, sensor-based home CR platform and provides ...
Human motion analysis technologies have been widely employed to identify injury determining facto... more Human motion analysis technologies have been widely employed to identify injury determining factors and provide objective and quantitative feedback to athletes to help prevent injury. However, most of these technologies are: expensive , restricted to laboratory environments, and can require significant post processing. This reduces their ecological validity, adoption and usefulness. In this paper, we present a novel wearable inertial sensor framework to accurately distinguish between symmetrical and asymmetrical running patterns in an unconstrained environment. The framework can automatically classify symmetry/asymmetry using Short Time Fourier Transform (STFT) and other time domain features in conjunction with a customized Random Forest classifier. The accuracy of the designed framework is up to 94% using 3-D accelerometer and 3-D gyroscope data from a sensor node attached on the upper back of a subject. The upper back inertial sensors data were then down-sampled by a factor of 4 t...
Purpose: To evaluate the effects of an eight week combined minimalist footwear (MFW) and gait-ret... more Purpose: To evaluate the effects of an eight week combined minimalist footwear (MFW) and gait-retraining intervention on running economy (RE) and kinematics in conventional footwear runners. Methods: Twenty-three trained male runners (age: 43 ± 10 years, stature: 177.2 ± 9.2 cm, body mass: 72.8 ± 10.2 kg, _ VO 2max : 56.5 ± 7.0 mL min À1 kg À1) were recruited. Participants were assigned to either an intervention group (n = 13) who gradually increased exposure to MFW and also implemented gait-retraining over an eight week period. RE and kinematics were measured in both MFW and conventional running shoes (CRS) at pre-tests and eight weeks, in a random order. In contrast the control group (n = 10) had no MFW exposure or gait retraining and were only tested in CRS. Results: The MFW and gait retraining intervention had no effect on RE (p < .001). However, RE was significantly better in MFW (mean difference 2.72%; p = .002) at both pre and post-tests compared to CRS. Step frequency increased as a result of the intervention (+5.7 steps per minute [spm]; p < .001), and was also significantly higher in MFW vs. CRS (+7.5 spm; p < .001). Conclusion: Whilst a better RE in MFW was observed when compared to CRS due to shoe mass, familiarization to MFW with gait-retraining was not found to influence RE.
The purpose of this study was to assess the effect of direct vibration during two sub-maximal iso... more The purpose of this study was to assess the effect of direct vibration during two sub-maximal isometric loading conditions on electromyographic output. Sixteen participants performed isometric knee extensions, at an angle of 150°, under four conditions in random order: 1) a load of 10% one repetition maximum (1 RM) with no vibration (10%+NV); 2) a load of 30% 1RM with
To evaluate the effects of an eight week combined minimalist footwear (MFW) and gait-retraining i... more To evaluate the effects of an eight week combined minimalist footwear (MFW) and gait-retraining intervention on running economy (RE) and kinematics in conventional footwear runners. Twenty-three trained male runners (age: 43±10years, stature: 177.2±9.2cm, body mass: 72.8±10.2kg, V̇O2max: 56.5±7.0mLmin(-1)kg(-1)) were recruited. Participants were assigned to either an intervention group (n=13) who gradually increased exposure to MFW and also implemented gait-retraining over an eight week period. RE and kinematics were measured in both MFW and conventional running shoes (CRS) at pre-tests and eight weeks, in a random order. In contrast the control group (n=10) had no MFW exposure or gait retraining and were only tested in CRS. The MFW and gait re-training intervention had no effect on RE (p&amp;amp;amp;amp;lt;.001). However, RE was significantly better in MFW (mean difference 2.72%; p=.002) at both pre and post-tests compared to CRS. Step frequency increased as a result of the intervention (+5.7 steps per minute [spm]; p&amp;amp;amp;amp;lt;.001), and was also significantly higher in MFW vs. CRS (+7.5spm; p&amp;amp;amp;amp;lt;.001). Whilst a better RE in MFW was observed when compared to CRS due to shoe mass, familiarization to MFW with gait-retraining was not found to influence RE.
There is a lack of epidemiological research in adolescent Gaelic games, with previous research pr... more 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. Prospective cohort study. 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. 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. 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.
The aim of this study was to assess and compare the ability of discrete point analysis (DPA), fun... more The aim of this study was to assess and compare the ability of discrete point analysis (DPA), functional principal component analysis (fPCA) and analysis of characterizing phases (ACP) to describe a dependent variable (jump height) using vertical ground reaction force curves captured during the propulsion phase of a countermovement jump. FPCA and ACP are continuous data analysis techniques that reduce the dimensionality of a data set by identifying phases of variation (key phases), which are used to generate subject scores that describe a subject's behavior. A stepwise multiple regression analysis was used to measure the ability to describe jump height of each data analysis technique. Findings indicated that the order of effectiveness (high to low) across the examined techniques was: ACP (99%), fPCA (78%) and DPA (21%). DPA was outperformed by fPCA and ACP because it can inadvertently compare unrelated features, does not analyze the whole data set and cannot examine important fe...
Journal of AAPOS : the official publication of the American Association for Pediatric Ophthalmology and Strabismus / American Association for Pediatric Ophthalmology and Strabismus, 2014
There is currently no universally accepted grading system for describing retinal hemorrhages (RH)... more There is currently no universally accepted grading system for describing retinal hemorrhages (RH) in abusive head trauma (AHT). The purpose of this study was to devise and evaluate a novel grading system and descriptive nomenclature for RH in AHT for clinical and research purposes. A traumatic hemorrhagic retinopathy (THR) grading system was developed for assessing and quantitatively analyzing retinal findings in abusive head trauma. The criteria for the THR grade included the extent, spread, and morphology of RH. Extent was classified as region 1 (posterior pole) or region 2 (peripheral). Spread, based on number of retinal hemorrhages, was classified as mild (10 or fewer RH), moderate (more than 10 RH) and severe (more than half of involved regions covered by RH). Morphology was classified by its intraretinal or extraretinal involvement. Two independent graders calculated the THR grade from RetCam images of 38 eyes of 19 patients <3 years of age with retinal hemorrhages associat...
To review systematically the diagnostic accuracy of various ocular signs for pediatric abusive he... more To review systematically the diagnostic accuracy of various ocular signs for pediatric abusive head trauma (AHT). Intraocular hemorrhages (IOH), perimacular retinal folds, traumatic retinoschisis and optic nerve sheath hemorrhages have been reported as cardinal signs of AHT. The evidence base supporting the accuracy of this interpretation, however, has not been systematically reviewed. A systematic keyword search of MEDLINE, EMBASE, and Evidence-Based Medicine Reviews was conducted for original studies reporting ocular findings in AHT. Articles were graded using a checklist for systematic reviews of diagnostic accuracy. The initial search yielded 971 articles, of which 55 relevant studies were graded, and 20 studies met inclusion criteria and were included in the review. The overall sensitivity of IOH for AHT was 75% and their specificity was 94%. Intraretinal hemorrhage at the posterior pole was the most common finding, although extensive, bilateral, and multilayered IOH were the most specific for AHT. Optic nerve sheath hemorrhages had a sensitivity and specificity for AHT of 72% and 71%, respectively. Traumatic retinoschisis and perimacular retinal folds were reported in 8% and 14% of AHT, respectively, but were not reported in other conditions. Prospective, consecutive studies confirm that IOH in infants-particularly bilateral, extensive, and multilayered-are highly specific for AHT. Optic nerve sheath hemorrhages are significantly more common in AHT than in other conditions, in autopsy studies. Traumatic retinoschisis and perimacular folds are present in a minority of AHT, but rarely seen in other conditions.
The principle of specificity suggests that it may be beneficial to undertake plyometric drop-jump... more The principle of specificity suggests that it may be beneficial to undertake plyometric drop-jump training when fatigued. However, this may increase peak-impact accelerations and therefore increase the risk of injury. The aims of the study were to determine if whole-body fatigue (i) increased peak-impact acceleration on the proximal tibia during plyometric drop jumps and (ii) produced associated changes in knee-joint kinematics during landing. Fifteen physically active male subjects performed drop jumps (30 and 50 cm) when nonfatigued and when fatigued. Whole-body fatigue was induced using a treadmill running protocol that incrementally increased effort. Peak-impact acceleration was measured with an accelerometer attached to the proximal tibia. Knee-joint kinematics were assessed during the eccentric phase: angle at initial touch down, maximum angle of flexion, range of motion, and peak angular velocity. Fatigue caused a significant increase in tibial impact acceleration and peak angular velocity in drop jumps from 30 cm (154.9 +/- 93.8 vs 192.6 +/- 103.9 m x s(-2): 24%; 675.3 +/- 60.7 vs 811.4 +/- 68.9 degrees x s(-1): 20%), but not from 50 cm (222.4 +/- 74.9 vs 234.1 +/- 83.9 m x s(-2): 5%; 962.0 +/- 189.0 vs 984.4 +/- 189.3 degrees x s(-1): 2.6%), with no associated change in the knee-joint angles assessed. It was argued, however, that rather than the neuromuscular system being selectively affected by fatigue at 30 cm and not 50 cm, drop jumps from 50 cm resulted in larger-impact accelerations with the neuromuscular system having only a limited ability to attenuate them per se, whether fatigued or nonfatigued. Care should be taken when performing drop jumps from a height of 30 cm in a fatigued state because of the reduced capacity to attenuate impact accelerations at the tibia, which may be associated with an increased risk of injury.
The effectiveness of vertical drop jumps (VDJs) to screen for non-contact ACL injuries is unclear... more 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 (η(2) = 0.165), external rotator (η(2) = 0.113) and valgus (η(2) = 0.126) moments and greater hip (η(2) = 0.062) and knee (η(2) = 0.080) flexion. The dominant limb generated greater knee flexor (η(2) = 0.062), external rotator (η(2) = 0.110) and valgus (η(2) = 0.065) moments. The HIIP only had one effect, increased thoracic flexion relative to the pelvis (η(2) = 0.088). Finally, the dominant limb demonstrated greater knee extensor moments during the second landing (η(2) = 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.
Exercise-based cardiac rehabilitation (CR) independently alters the clinical course of cardiovasc... more Exercise-based cardiac rehabilitation (CR) independently alters the clinical course of cardiovascular diseases resulting in a significant reduction in all-cause and cardiac mortality. However, only 15%-30% of all eligible patients participate in a phase 2 ambulatory programme. The uptake rate of community-based programmes following phase 2 CR and adherence to long-term exercise is extremely poor. Newer care models, involving telerehabilitation programmes that are delivered remotely, show considerable promise for increasing adherence. In this view, the PATHway (Physical Activity Towards Health) platform was developed and now needs to be evaluated in terms of its feasibility and clinical efficacy. In a multicentre randomised controlled pilot trial, 120 participants (m/f, age 40-80 years) completing a phase 2 ambulatory CR programme will be randomised on a 1:1 basis to PATHway or usual care. PATHway involves a comprehensive, internet-enabled, sensor-based home CR platform and provides ...
Human motion analysis technologies have been widely employed to identify injury determining facto... more Human motion analysis technologies have been widely employed to identify injury determining factors and provide objective and quantitative feedback to athletes to help prevent injury. However, most of these technologies are: expensive , restricted to laboratory environments, and can require significant post processing. This reduces their ecological validity, adoption and usefulness. In this paper, we present a novel wearable inertial sensor framework to accurately distinguish between symmetrical and asymmetrical running patterns in an unconstrained environment. The framework can automatically classify symmetry/asymmetry using Short Time Fourier Transform (STFT) and other time domain features in conjunction with a customized Random Forest classifier. The accuracy of the designed framework is up to 94% using 3-D accelerometer and 3-D gyroscope data from a sensor node attached on the upper back of a subject. The upper back inertial sensors data were then down-sampled by a factor of 4 t...
Purpose: To evaluate the effects of an eight week combined minimalist footwear (MFW) and gait-ret... more Purpose: To evaluate the effects of an eight week combined minimalist footwear (MFW) and gait-retraining intervention on running economy (RE) and kinematics in conventional footwear runners. Methods: Twenty-three trained male runners (age: 43 ± 10 years, stature: 177.2 ± 9.2 cm, body mass: 72.8 ± 10.2 kg, _ VO 2max : 56.5 ± 7.0 mL min À1 kg À1) were recruited. Participants were assigned to either an intervention group (n = 13) who gradually increased exposure to MFW and also implemented gait-retraining over an eight week period. RE and kinematics were measured in both MFW and conventional running shoes (CRS) at pre-tests and eight weeks, in a random order. In contrast the control group (n = 10) had no MFW exposure or gait retraining and were only tested in CRS. Results: The MFW and gait retraining intervention had no effect on RE (p < .001). However, RE was significantly better in MFW (mean difference 2.72%; p = .002) at both pre and post-tests compared to CRS. Step frequency increased as a result of the intervention (+5.7 steps per minute [spm]; p < .001), and was also significantly higher in MFW vs. CRS (+7.5 spm; p < .001). Conclusion: Whilst a better RE in MFW was observed when compared to CRS due to shoe mass, familiarization to MFW with gait-retraining was not found to influence RE.
The purpose of this study was to assess the effect of direct vibration during two sub-maximal iso... more The purpose of this study was to assess the effect of direct vibration during two sub-maximal isometric loading conditions on electromyographic output. Sixteen participants performed isometric knee extensions, at an angle of 150°, under four conditions in random order: 1) a load of 10% one repetition maximum (1 RM) with no vibration (10%+NV); 2) a load of 30% 1RM with
To evaluate the effects of an eight week combined minimalist footwear (MFW) and gait-retraining i... more To evaluate the effects of an eight week combined minimalist footwear (MFW) and gait-retraining intervention on running economy (RE) and kinematics in conventional footwear runners. Twenty-three trained male runners (age: 43±10years, stature: 177.2±9.2cm, body mass: 72.8±10.2kg, V̇O2max: 56.5±7.0mLmin(-1)kg(-1)) were recruited. Participants were assigned to either an intervention group (n=13) who gradually increased exposure to MFW and also implemented gait-retraining over an eight week period. RE and kinematics were measured in both MFW and conventional running shoes (CRS) at pre-tests and eight weeks, in a random order. In contrast the control group (n=10) had no MFW exposure or gait retraining and were only tested in CRS. The MFW and gait re-training intervention had no effect on RE (p&amp;amp;amp;amp;lt;.001). However, RE was significantly better in MFW (mean difference 2.72%; p=.002) at both pre and post-tests compared to CRS. Step frequency increased as a result of the intervention (+5.7 steps per minute [spm]; p&amp;amp;amp;amp;lt;.001), and was also significantly higher in MFW vs. CRS (+7.5spm; p&amp;amp;amp;amp;lt;.001). Whilst a better RE in MFW was observed when compared to CRS due to shoe mass, familiarization to MFW with gait-retraining was not found to influence RE.
There is a lack of epidemiological research in adolescent Gaelic games, with previous research pr... more 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. Prospective cohort study. 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. 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. 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.
The aim of this study was to assess and compare the ability of discrete point analysis (DPA), fun... more The aim of this study was to assess and compare the ability of discrete point analysis (DPA), functional principal component analysis (fPCA) and analysis of characterizing phases (ACP) to describe a dependent variable (jump height) using vertical ground reaction force curves captured during the propulsion phase of a countermovement jump. FPCA and ACP are continuous data analysis techniques that reduce the dimensionality of a data set by identifying phases of variation (key phases), which are used to generate subject scores that describe a subject's behavior. A stepwise multiple regression analysis was used to measure the ability to describe jump height of each data analysis technique. Findings indicated that the order of effectiveness (high to low) across the examined techniques was: ACP (99%), fPCA (78%) and DPA (21%). DPA was outperformed by fPCA and ACP because it can inadvertently compare unrelated features, does not analyze the whole data set and cannot examine important fe...
Journal of AAPOS : the official publication of the American Association for Pediatric Ophthalmology and Strabismus / American Association for Pediatric Ophthalmology and Strabismus, 2014
There is currently no universally accepted grading system for describing retinal hemorrhages (RH)... more There is currently no universally accepted grading system for describing retinal hemorrhages (RH) in abusive head trauma (AHT). The purpose of this study was to devise and evaluate a novel grading system and descriptive nomenclature for RH in AHT for clinical and research purposes. A traumatic hemorrhagic retinopathy (THR) grading system was developed for assessing and quantitatively analyzing retinal findings in abusive head trauma. The criteria for the THR grade included the extent, spread, and morphology of RH. Extent was classified as region 1 (posterior pole) or region 2 (peripheral). Spread, based on number of retinal hemorrhages, was classified as mild (10 or fewer RH), moderate (more than 10 RH) and severe (more than half of involved regions covered by RH). Morphology was classified by its intraretinal or extraretinal involvement. Two independent graders calculated the THR grade from RetCam images of 38 eyes of 19 patients <3 years of age with retinal hemorrhages associat...
To review systematically the diagnostic accuracy of various ocular signs for pediatric abusive he... more To review systematically the diagnostic accuracy of various ocular signs for pediatric abusive head trauma (AHT). Intraocular hemorrhages (IOH), perimacular retinal folds, traumatic retinoschisis and optic nerve sheath hemorrhages have been reported as cardinal signs of AHT. The evidence base supporting the accuracy of this interpretation, however, has not been systematically reviewed. A systematic keyword search of MEDLINE, EMBASE, and Evidence-Based Medicine Reviews was conducted for original studies reporting ocular findings in AHT. Articles were graded using a checklist for systematic reviews of diagnostic accuracy. The initial search yielded 971 articles, of which 55 relevant studies were graded, and 20 studies met inclusion criteria and were included in the review. The overall sensitivity of IOH for AHT was 75% and their specificity was 94%. Intraretinal hemorrhage at the posterior pole was the most common finding, although extensive, bilateral, and multilayered IOH were the most specific for AHT. Optic nerve sheath hemorrhages had a sensitivity and specificity for AHT of 72% and 71%, respectively. Traumatic retinoschisis and perimacular retinal folds were reported in 8% and 14% of AHT, respectively, but were not reported in other conditions. Prospective, consecutive studies confirm that IOH in infants-particularly bilateral, extensive, and multilayered-are highly specific for AHT. Optic nerve sheath hemorrhages are significantly more common in AHT than in other conditions, in autopsy studies. Traumatic retinoschisis and perimacular folds are present in a minority of AHT, but rarely seen in other conditions.
The principle of specificity suggests that it may be beneficial to undertake plyometric drop-jump... more The principle of specificity suggests that it may be beneficial to undertake plyometric drop-jump training when fatigued. However, this may increase peak-impact accelerations and therefore increase the risk of injury. The aims of the study were to determine if whole-body fatigue (i) increased peak-impact acceleration on the proximal tibia during plyometric drop jumps and (ii) produced associated changes in knee-joint kinematics during landing. Fifteen physically active male subjects performed drop jumps (30 and 50 cm) when nonfatigued and when fatigued. Whole-body fatigue was induced using a treadmill running protocol that incrementally increased effort. Peak-impact acceleration was measured with an accelerometer attached to the proximal tibia. Knee-joint kinematics were assessed during the eccentric phase: angle at initial touch down, maximum angle of flexion, range of motion, and peak angular velocity. Fatigue caused a significant increase in tibial impact acceleration and peak angular velocity in drop jumps from 30 cm (154.9 +/- 93.8 vs 192.6 +/- 103.9 m x s(-2): 24%; 675.3 +/- 60.7 vs 811.4 +/- 68.9 degrees x s(-1): 20%), but not from 50 cm (222.4 +/- 74.9 vs 234.1 +/- 83.9 m x s(-2): 5%; 962.0 +/- 189.0 vs 984.4 +/- 189.3 degrees x s(-1): 2.6%), with no associated change in the knee-joint angles assessed. It was argued, however, that rather than the neuromuscular system being selectively affected by fatigue at 30 cm and not 50 cm, drop jumps from 50 cm resulted in larger-impact accelerations with the neuromuscular system having only a limited ability to attenuate them per se, whether fatigued or nonfatigued. Care should be taken when performing drop jumps from a height of 30 cm in a fatigued state because of the reduced capacity to attenuate impact accelerations at the tibia, which may be associated with an increased risk of injury.
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Papers by Kieran Moran