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Does an Increase in Supraspinatus Tendon Thickness After Swimming Increase the Likelihood of Future Shoulder Pain? Sports Health 2024; 16:358-362. [PMID: 37946512 PMCID: PMC11025504 DOI: 10.1177/19417381231208715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023] Open
Abstract
BACKGROUND Increase in supraspinatus tendon thickness (STT) resulting from swimming practice has been observed in those with a history of shoulder pain. The magnitude of change in STT after a swimming session and its rate of recovery may be an indicator of future shoulder pain incidence. HYPOTHESIS The supraspinatus tendons that demonstrate a greater increase in thickness as a result of swimming practice will have an increased likelihood of future shoulder pain in a cohort of competitive swimmers over a period of 6 months. DESIGN Descriptive epidemiology study. LEVEL OF EVIDENCE Level 2b, individual cohort studies. METHODS A cohort of 50 nationally qualified swimmers aged between 14 and 22 years, from 3 open National Swimming Programs in Victoria, Australia, were recruited for this study. Ultrasonographic measurements of swimmers' STT was obtained of both shoulders, before, immediately after, and 6 hours after a single swimming practice session. Data were recorded of any significant interfering shoulder pain at 3 and 6 months after the initial testing session. RESULTS Stepwise logistic regression models indicated that significant predictors of the likelihood of experiencing significant interfering pain were sex [significant at 6 months; odds ratio (OR) 4.2] and the extent of change in STT immediately (OR 2.3 and 1.3 per mm at 3 and 6 months, respectively) and 6 hours postpractice (OR 1.9 and 1.5 per mm at 3 and 6 months, respectively). CONCLUSION The current data suggest larger increases in tendon thickness after training are associated with an increased likelihood of future shoulder pain. CLINICAL RELEVANCE These data may be valuable for monitoring training load and identifying athletes who may have an increased likelihood of shoulder pain.
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Characterising gluteal muscle forces during hip-focused injury prevention & rehabilitation exercises. J Sci Med Sport 2022. [DOI: 10.1016/j.jsams.2022.09.087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Mechanical, Material and Morphological Adaptations of Healthy Lower Limb Tendons to Mechanical Loading: A Systematic Review and Meta-Analysis. Sports Med 2022; 52:2405-2429. [PMID: 35657492 PMCID: PMC9474511 DOI: 10.1007/s40279-022-01695-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/20/2022] [Indexed: 11/22/2022]
Abstract
BACKGROUND Exposure to increased mechanical loading during physical training can lead to increased tendon stiffness. However, the loading regimen that maximises tendon adaptation and the extent to which adaptation is driven by changes in tendon material properties or tendon geometry is not fully understood. OBJECTIVE To determine (1) the effect of mechanical loading on tendon stiffness, modulus and cross-sectional area (CSA); (2) whether adaptations in stiffness are driven primarily by changes in CSA or modulus; (3) the effect of training type and associated loading parameters (relative intensity; localised strain, load duration, load volume and contraction mode) on stiffness, modulus or CSA; and (4) whether the magnitude of adaptation in tendon properties differs between age groups. METHODS Five databases (PubMed, Scopus, CINAHL, SPORTDiscus, EMBASE) were searched for studies detailing load-induced adaptations in tendon morphological, material or mechanical properties. Standardised mean differences (SMDs) with 95% confidence intervals (CIs) were calculated and data were pooled using a random effects model to estimate variance. Meta regression was used to examine the moderating effects of changes in tendon CSA and modulus on tendon stiffness. RESULTS Sixty-one articles met the inclusion criteria. The total number of participants in the included studies was 763. The Achilles tendon (33 studies) and the patella tendon (24 studies) were the most commonly studied regions. Resistance training was the main type of intervention (49 studies). Mechanical loading produced moderate increases in stiffness (standardised mean difference (SMD) 0.74; 95% confidence interval (CI) 0.62-0.86), large increases in modulus (SMD 0.82; 95% CI 0.58-1.07), and small increases in CSA (SMD 0.22; 95% CI 0.12-0.33). Meta-regression revealed that the main moderator of increased stiffness was modulus. Resistance training interventions induced greater increases in modulus than other training types (SMD 0.90; 95% CI 0.65-1.15) and higher strain resistance training protocols induced greater increases in modulus (SMD 0.82; 95% CI 0.44-1.20; p = 0.009) and stiffness (SMD 1.04; 95% CI 0.65-1.43; p = 0.007) than low-strain protocols. The magnitude of stiffness and modulus differences were greater in adult participants. CONCLUSIONS Mechanical loading leads to positive adaptation in lower limb tendon stiffness, modulus and CSA. Studies to date indicate that the main mechanism of increased tendon stiffness due to physical training is increased tendon modulus, and that resistance training performed at high compared to low localised tendon strains is associated with the greatest positive tendon adaptation. PROSPERO registration no.: CRD42019141299.
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Relationships between trunk morphology and strength with non-contact lower limb injuries in elite rugby league and Australian football players. J Sci Med Sport 2021. [DOI: 10.1016/j.jsams.2021.09.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Cross-sectional Study of EMG and EMG Rise During Fast and Slow Hamstring Exercises. Int J Sports Phys Ther 2021; 16:1033-1042. [PMID: 34386282 PMCID: PMC8329323 DOI: 10.26603/001c.25364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Accepted: 02/21/2021] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Hamstring injuries remain a major burden in football while the effective prevention exercise the Nordic Hamstring is poorly adopted, despite the added positive effects on performance. Better understanding of hamstring function during Nordic Hamstring compared to other exercises may provide better insight to the physiological adaptations of different types of hamstring curls. PURPOSE This cross-sectional study therefore aimed to compare the Nordic Hamstring curl with a conventional prone Leg Curl at different loads, and novel high velocity Hamstring Catches; in terms of peak normalized electromyographical activity (nEMG) and rate of electromyographic rise (RER) of Biceps Femoris long head, and angular velocity of the knee. STUDY DESIGN Cross-sectional study. METHODS Out of 28 participants enrolled, the final sample included 23 recreationally active male participants who attended a session for determining RM (repetition maximum) to establish loading (8 and 16RM for Hamstring Catches, and 8, 16 and 24RM for Leg Curl) and to familiarize themselves with the three different exercises (Nordic Hamstring, Leg Curl and Hamstring Catch), and a testing session >4 days after during which EMG data were collected during 3 repetitions of each exercise performed in a random order. RESULTS The Nordic Hamstring evoked higher RER (1091.8 nEMG/s) than Hamstring Catches (mean difference: 421 nEMG/s, p<0.0001) and Leg Curl (mean difference: 705 nEMG/s, p<0.001), and at the earliest numerical timepoint from onset of muscle contraction (the Nordic Hamstring: 6 ms; Hamstring Catches: 36-41 ms; Leg Curl: 12-14 ms). Hamstring Catches displayed high peak angular velocity (mean: 471°/s). There was no difference in peak nEMG, irrespective of load for Leg Curl (8, 16 or 24RM) or Hamstring Catches (8- or 16RM). CONCLUSION The Nordic Hamstring displayed the highest level muscle activity and most explosive recruitment characteristics with early and high rate of electromyographic rise, compared to even high velocity exercises, thus providing a possible mechanism by which it may increase performance and reduce injuries. LEVELS OF EVIDENCE 3. WHAT IS KNOWN ABOUT THE SUBJECT Early phase force and muscle recruitment have been linked to both performance and hamstring-related inhibition and fatiguability. However, the potential for different hamstring exercises to elicit explosive recruitment is unknown. WHAT THIS STUDY ADDS TO EXISTING KNOWLEDGE Early phase recruitment was higher and faster during the Nordic Hamstring exercise compared with conventional hamstring Leg Curl exercises with different loads and a high-velocity hamstring exercise. CLINICAL RELEVANCE The surprisingly fast and explosive recruitment characteristics during the Nordic Hamstring exercise suggests the possibility that this exercise have the potential to improve the rate of force development and perhaps counter the effects of hamstring-related inhibition and fatigue.
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Performance changes during the off-season period in football players - Effects of age and previous hamstring injury. J Sports Sci 2020; 38:2489-2499. [PMID: 32658565 DOI: 10.1080/02640414.2020.1792160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The aims of this study were to investigate changes in selected performance measures during an off-season period, their association, and the potential role of age and previous hamstring injury in semi-professional and amateur football players. Seventy-four male players (age: 25 ± 4 years, stature: 178.0 ± 6.6 cm, body mass: 74.9 ± 8.1 kg) were assessed at the beginning and end of the off-season summer-period for sprint, change-of-direction performance and eccentric hamstring strength. Small to medium increases in sprint times were observed at 5 (d = 0.26, p = 0.057), 10 (d = 0.42, p < 0.001) and 30 m (d = 0.64, p < 0.001). Small (d = -0.23, p = 0.033) improvements were observed for COD performance, and no changes in eccentric hamstring strength (d = 0.10, p = 0.317). The changes in the outcomes were not affected by age (p = 0.449 to 0.928) or previous hamstring injury (p = 0.109 to 0.995). The impaired sprint performance was not related to changes in eccentric hamstring strength (r = -0.21 to 0.03, p = 0.213 to 0.856), instead, changes in COD performance were associated with changes in eccentric hamstring strength (r = -0.42, p = 0.008).
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ECCENTRIC HAMSTRING STRENGTH IS ASSOCIATED WITH AGE AND DURATION OF PREVIOUS SEASON HAMSTRING INJURY IN MALE SOCCER PLAYERS. Int J Sports Phys Ther 2020; 15:246-253. [PMID: 32269858 PMCID: PMC7134347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023] Open
Abstract
BACKGROUND Eccentric hamstring strength seems important in reducing the odds of future hamstring injuries. While age and previous injury are well-known risk factors for future hamstring injuries, the association of age and previous hamstring injury with eccentric hamstring strength in the following season is unknown. PURPOSE To investigate the association of age and previous hamstring injury with preseason eccentric hamstring strength in soccer players, and to investigate the association between previous hamstring injury duration and preseason eccentric hamstring strength. STUDY DESIGN Descriptive, cross-sectional study. METHODS A convenience sample of 284 male amateur soccer players (age 18-38 years) was included in the analyses. Self-reported information about previous season hamstring injury and its duration (three weeks or less; more than three weeks) was collected. Preseason eccentric hamstring strength was obtained during the Nordic hamstring exercise using a field-based device. RESULTS Age had a negative association with preseason eccentric hamstring strength with 0.9% reduction per year. Players with a previous hamstring injury duration of more than three weeks (n=27) had 13% lower preseason eccentric hamstring strength compared to players without previous hamstring injury. CONCLUSION Older players have lower preseason eccentric hamstring strength than younger players. Players with a previous hamstring injury duration of more than three weeks have lower preseason eccentric hamstring strength than the rest of the players. These results highlight the need to monitor and address the identified weaknesses in eccentric hamstring strength in amateur soccer players, with specific emphasis on older players with a previous hamstring injury of longer duration. LEVEL OF EVIDENCE 2b.
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Hamstring muscle activation and morphology are significantly altered 1 to 6 years after anterior cruciate ligament reconstruction with semitendinosus graft. J Sci Med Sport 2019. [DOI: 10.1016/j.jsams.2019.08.257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Reply to Li et al. Int J Sports Med 2018; 39:408. [DOI: 10.1055/a-0586-2257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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A functional MRI Exploration of Hamstring Activation During the Supine Bridge Exercise. Int J Sports Med 2017; 39:104-109. [DOI: 10.1055/s-0043-121150] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AbstractThe single leg supine bridge (SLB) is a commonly employed strengthening exercise and is used as a clinical test for hamstring function in sports, however, little is known about the patterns of muscle activation in this task. To explore these activation patterns, nine healthy, recreationally active males underwent functional magnetic resonance imaging (fMRI) of their thighs at rest and immediately after 5 sets of 10 repetitions of the SLB exercise. Exercise-induced increases in the transverse (T2) relaxation time of the biceps femoris long and short heads, semitendinosus and semimembranosus, were determined via signal intensity changes in pre- and post-exercise images and used as an index of muscle activation. The Bonferroni adjusted alpha was set at p<0.008. The semitendinosus exhibited a greater T2 increase than the biceps femoris short head (p<0.001, d=2.0) and semimembranosus (p=0.001, d=1.2), but not biceps femoris long head (p=0.029, d=0.9). Furthermore, the percentage change in T2 for biceps femoris long head was greater than its short head (p=0.003, d=1.4). During the SLB exercise, the semitendinosus is most selectively targeted and the biceps femoris long head is preferentially activated over its short head. These findings may have implications for the use of the SLB in hamstring injury prevention and rehabilitation programs.
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THE EFFECT OF REPETITIVE KICKING ON KNEE FLEXOR NEUROMUSCULAR FUNCTION. Br J Sports Med 2017. [DOI: 10.1136/bjsports-2016-097372.77] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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THE EFFECT OF EXERCISE PRESCRIPTION ON FORCE OUTPUT AND MUSCLE ACTIVATION DURING THE NORDIC HAMSTRING EXERCISE. Br J Sports Med 2017. [DOI: 10.1136/bjsports-2016-097372.54] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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IMPACT OF THE NORDIC HAMSTRING AND HIP EXTENSION EXERCISES ON HAMSTRING ARCHITECTURE AND MORPHOLOGY: IMPLICATIONS FOR INJURY PREVENTION. Br J Sports Med 2017. [DOI: 10.1136/bjsports-2016-097372.43] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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ECCENTRIC KNEE FLEXOR STRENGTH AND HAMSTRING INJURY RISK IN ATHLETES WITH HISTORY OF ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION. Br J Sports Med 2017. [DOI: 10.1136/bjsports-2016-097372.200] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Knee flexor muscle use during hip extension and the Nordic hamstring exercise: An fMRI study. J Sci Med Sport 2017. [DOI: 10.1016/j.jsams.2017.01.221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Abstract
BACKGROUND This study examined relationships between adiposity, physical functioning, and physical activity. METHODS Obese (N = 107) and healthy-weight (N = 132) children aged 10-13 years underwent assessments of percent body fat (%BF, dual energy X-ray absorptiometry); knee extensor strength (KE, isokinetic dynamometry); cardiorespiratory fitness (CRF, peak oxygen uptake by cycle ergometry); physical health-related quality of life (HRQOL); and worst pain intensity and walking capacity [six-minute walk (6MWT)]. Structural equation modelling was used to assess relationships between variables. RESULTS Moderate relationships were observed between %BF and (1) 6MWT, (2) KE strength corrected for mass, and (3) CRF relative to mass (r -0.36 to -0.69, p ≤ 0.007). Weak relationships were found between %BF and physical HRQOL (r -0.27, p = 0.008); CRF relative to mass and physical HRQOL (r -0.24, p = 0.003); physical activity and 6MWT (r 0.17, p = 0.004). Squared multiple correlations showed that 29.6% variance in physical HRQOL was explained by %BF, pain, and CRF relative to mass; while 28.0% variance in 6MWT was explained by %BF and physical activity. CONCLUSIONS It appears that children with a higher body fat percentage have poorer KE strength, CRF, and overall physical functioning. Reducing percent fat appears to be the best target to improve functioning. However, a combined approach to intervention, targeting reductions in body fat percentage, reductions in pain, and improvements in physical activity and CRF may assist physical functioning.
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Hamstring strain injury – Structural and functional considerations for prevention, rehabilitation and return to play. J Sci Med Sport 2015. [DOI: 10.1016/j.jsams.2015.12.386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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A novel approach to predict repeatability of performance in older adults: Coefficients of variation for strength and functional measures. J Sci Med Sport 2015. [DOI: 10.1016/j.jsams.2015.12.456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Architectural adaptations of the biceps femoris long head following concentric and eccentric resistance training: A randomised control trial. J Sci Med Sport 2015. [DOI: 10.1016/j.jsams.2015.12.431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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High intensity running increases risk of hamstring strain injury in elite Australian rules footballers. J Sci Med Sport 2015. [DOI: 10.1016/j.jsams.2015.12.178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training. J Physiol 2015; 593:4285-301. [PMID: 26174323 DOI: 10.1113/jp270570] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 07/02/2015] [Indexed: 01/10/2023] Open
Abstract
We investigated functional, morphological and molecular adaptations to strength training exercise and cold water immersion (CWI) through two separate studies. In one study, 21 physically active men strength trained for 12 weeks (2 days per week), with either 10 min of CWI or active recovery (ACT) after each training session. Strength and muscle mass increased more in the ACT group than in the CWI group (P < 0.05). Isokinetic work (19%), type II muscle fibre cross-sectional area (17%) and the number of myonuclei per fibre (26%) increased in the ACT group (all P < 0.05), but not the CWI group. In another study, nine active men performed a bout of single-leg strength exercises on separate days, followed by CWI or ACT. Muscle biopsies were collected before and 2, 24 and 48 h after exercise. The number of satellite cells expressing neural cell adhesion molecule (NCAM) (10-30%) and paired box protein (Pax7) (20-50%) increased 24-48 h after exercise with ACT. The number of NCAM(+) satellite cells increased 48 h after exercise with CWI. NCAM(+) - and Pax7(+) -positive satellite cell numbers were greater after ACT than after CWI (P < 0.05). Phosphorylation of p70S6 kinase(Thr421/Ser424) increased after exercise in both conditions but was greater after ACT (P < 0.05). These data suggest that CWI attenuates the acute changes in satellite cell numbers and activity of kinases that regulate muscle hypertrophy, which may translate to smaller long-term training gains in muscle strength and hypertrophy. The use of CWI as a regular post-exercise recovery strategy should be reconsidered.
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Acute injuries in track and field athletes: a 3-year observational study at the Penn Relays Carnival with epidemiology and medical coverage implications. Am J Sports Med 2015; 43:816-22. [PMID: 25560540 DOI: 10.1177/0363546514562553] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Few studies have examined acute injuries in track and field in both elite and subelite athletes. PURPOSE To observe the absolute number and relative rates of injury in track and field athletes across a wide range of competition levels and ages during 3 years of the Penn Relays Carnival to assist with future medical coverage planning and injury prevention strategies. STUDY DESIGN Descriptive epidemiology study. METHODS Over a 3-year period, all injuries treated by the medical staff were recorded on a standardized injury report form. Absolute number of injuries and relative injury rates (number of injuries per 1000 competing athletes) were determined and odds ratios (ORs) of injury rates were calculated between sexes, competition levels, and events. Injuries were also broken down into major or minor medical or orthopaedic injuries. RESULTS Throughout the study period, 48,473 competing athletes participated in the Penn Relays Carnival, and 436 injuries were sustained. For medical coverage purposes, the relative rate of injury subtypes was greatest for minor orthopaedic injuries (5.71 injuries per 1000 participants), followed by minor medical injuries (3.42 injuries per 1000 participants), major medical injuries (0.69 injuries per 1000 participants), and major orthopaedic injuries (0.18 injuries per 1000 participants). College/elite athletes displayed the lowest relative injury rate (7.99 injuries per 1000 participants), which was significantly less than that of high school (9.87 injuries per 1000 participants) and masters athletes (16.33 injuries per 1000 participants). Male athletes displayed a greater likelihood of having a minor orthopaedic injury compared with female athletes (OR, 1.36 [95% CI, 1.06-1.75]; χ2 = 5.73; P = .017) but were less likely to sustain a major medical injury (OR, 0.33 [95% CI, 0.15-0.75]; χ2 = 7.75; P = .005). Of the 3 most heavily participated in events, the 4 × 400-m relay displayed the greatest relative injury rate (13.6 injuries per 1000 participants) compared with the 4 × 100-m and 4 × 200-m relays. CONCLUSION Medical coverage teams for future large-scale track and field events need to plan for at least 2 major orthopaedic and 7 major medical injuries per 10,000 participants. Male track and field athletes, particularly masters male athletes, are at greater risk of injury compared with other sexes and competition levels.
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Differences exist in the architectural characteristics of the biceps femoris long head in previously injured individuals. J Sci Med Sport 2014. [DOI: 10.1016/j.jsams.2014.11.147] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hamstring muscle activation during high-speed overground running: Impact of previous strain injury. J Sci Med Sport 2014. [DOI: 10.1016/j.jsams.2014.11.218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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HAMSTRING MUSCLE ACTIVATION DURING HIGH-SPEED OVERGROUND RUNNING: IMPACT OF PREVIOUS STRAIN INJURY. Br J Sports Med 2014. [DOI: 10.1136/bjsports-2014-093494.32] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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PREVIOUS HAMSTRING INJURY REDUCES PRE-SEASON IMPROVEMENTS IN ECCENTRIC STRENGTH IN ELITE AUSTRALIAN FOOTBALL PLAYERS. Br J Sports Med 2014. [DOI: 10.1136/bjsports-2014-093494.268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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ECCENTRIC HAMSTRING STRENGTH DURING THE NORDIC HAMSTRING EXERCISES IS A RISK FACTOR FOR HAMSTRING STRAIN INJURY IN ELITE AUSTRALIAN FOOTBALL: A PROSPECTIVE COHORT STUDY. Br J Sports Med 2014. [DOI: 10.1136/bjsports-2014-093494.232] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Acute hamstring strain injury in track-and-field athletes: A 3-year observational study at the Penn Relay Carnival. Scand J Med Sci Sports 2013; 24:e254-9. [DOI: 10.1111/sms.12159] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2013] [Indexed: 11/28/2022]
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Hamstring muscle activation during the Nordic hamstring exercise and the impact of previous injury: An fMRI study. J Sci Med Sport 2013. [DOI: 10.1016/j.jsams.2013.10.101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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A novel field test of eccentric hamstring strength: A reliability and injury study. J Sci Med Sport 2013. [DOI: 10.1016/j.jsams.2013.10.098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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To the Editor. J Strength Cond Res 2013. [DOI: 10.1519/jsc.0b013e3182a8827c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Declines in eccentric knee flexor weakness following repeat sprint running are related to declines in biceps femoris voluntary activation. J Sci Med Sport 2012. [DOI: 10.1016/j.jsams.2012.11.153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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A 5-year study into hamstring strain injuries at the Penn Relay Carnivala. J Sci Med Sport 2012. [DOI: 10.1016/j.jsams.2012.11.316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Biceps femoris fascicle length is shorter in a previously hamstring injured athlete. J Sci Med Sport 2012. [DOI: 10.1016/j.jsams.2012.11.369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Differences in knee extensor strength in healthy-weight and obese children. Obes Res Clin Pract 2012. [DOI: 10.1016/j.orcp.2012.08.076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Influence of preexercise muscle glycogen content on transcriptional activity of metabolic and myogenic genes in well-trained humans. J Appl Physiol (1985) 2007; 102:1604-11. [PMID: 17218424 DOI: 10.1152/japplphysiol.01260.2006] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
To determine whether preexercise muscle glycogen content influences the transcription of several early-response genes involved in the regulation of muscle growth, seven male strength-trained subjects performed one-legged cycling exercise to exhaustion to lower muscle glycogen levels (Low) in one leg compared with the leg with normal muscle glycogen (Norm) and then the following day completed a unilateral bout of resistance training (RT). Muscle biopsies from both legs were taken at rest, immediately after RT, and after 3 h of recovery. Resting glycogen content was higher in the control leg (Norm leg) than in the Low leg (435 +/- 87 vs. 193 +/- 29 mmol/kg dry wt; P < 0.01). RT decreased glycogen content in both legs (P < 0.05), but postexercise values remained significantly higher in the Norm than the Low leg (312 +/- 129 vs. 102 +/- 34 mmol/kg dry wt; P < 0.01). GLUT4 (3-fold; P < 0.01) and glycogenin mRNA abundance (2.5-fold; not significant) were elevated at rest in the Norm leg, but such differences were abolished after exercise. Preexercise mRNA abundance of atrogenes was also higher in the Norm compared with the Low leg [atrogin: approximately 14-fold, P < 0.01; RING (really interesting novel gene) finger: approximately 3-fold, P < 0.05] but decreased for atrogin in Norm following RT (P < 0.05). There were no differences in the mRNA abundance of myogenic regulatory factors and IGF-I in the Norm compared with the Low leg. Our results demonstrate that 1) low muscle glycogen content has variable effects on the basal transcription of select metabolic and myogenic genes at rest, and 2) any differences in basal transcription are completely abolished after a single bout of heavy resistance training. We conclude that commencing resistance exercise with low muscle glycogen does not enhance the activity of genes implicated in promoting hypertrophy.
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Interaction of contractile activity and training history on mRNA abundance in skeletal muscle from trained athletes. Am J Physiol Endocrinol Metab 2006; 290:E849-55. [PMID: 16338907 DOI: 10.1152/ajpendo.00299.2005] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Skeletal muscle displays enormous plasticity to respond to contractile activity with muscle from strength- (ST) and endurance-trained (ET) athletes representing diverse states of the adaptation continuum. Training adaptation can be viewed as the accumulation of specific proteins. Hence, the altered gene expression that allows for changes in protein concentration is of major importance for any training adaptation. Accordingly, the aim of the present study was to quantify acute subcellular responses in muscle to habitual and unfamiliar exercise. After 24-h diet/exercise control, 13 male subjects (7 ST and 6 ET) performed a random order of either resistance (8 x 5 maximal leg extensions) or endurance exercise (1 h of cycling at 70% peak O2 uptake). Muscle biopsies were taken from vastus lateralis at rest and 3 h after exercise. Gene expression was analyzed using real-time PCR with changes normalized relative to preexercise values. After cycling exercise, peroxisome proliferator-activated receptor-gamma coactivator-1alpha (ET approximately 8.5-fold, ST approximately 10-fold, P < 0.001), pyruvate dehydrogenase kinase-4 (PDK-4; ET approximately 26-fold, ST approximately 39-fold), vascular endothelial growth factor (VEGF; ET approximately 4.5-fold, ST approximately 4-fold), and muscle atrophy F-box protein (MAFbx) (ET approximately 2-fold, ST approximately 0.4-fold) mRNA increased in both groups, whereas MyoD (approximately 3-fold), myogenin (approximately 0.9-fold), and myostatin (approximately 2-fold) mRNA increased in ET but not in ST (P < 0.05). After resistance exercise PDK-4 (approximately 7-fold, P < 0.01) and MyoD (approximately 0.7-fold) increased, whereas MAFbx (approximately 0.7-fold) and myostatin (approximately 0.6-fold) decreased in ET but not in ST. We conclude that prior training history can modify the acute gene responses in skeletal muscle to subsequent exercise.
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Abstract
Skeletal muscle from strength- and endurance-trained individuals represents diverse adaptive states. In this regard, AMPK-PGC-1alpha signaling mediates several adaptations to endurance training, while up-regulation of the Akt-TSC2-mTOR pathway may underlie increased protein synthesis after resistance exercise. We determined the effect of prior training history on signaling responses in seven strength-trained and six endurance-trained males who undertook 1 h cycling at 70% VO2peak or eight sets of five maximal repetitions of isokinetic leg extensions. Muscle biopsies were taken at rest, immediately and 3 h postexercise. AMPK phosphorylation increased after cycling in strength-trained (54%; P<0.05) but not endurance-trained subjects. Conversely, AMPK was elevated after resistance exercise in endurance- (114%; P<0.05), but not strength-trained subjects. Akt phosphorylation increased in endurance- (50%; P<0.05), but not strength-trained subjects after cycling but was unchanged in either group after resistance exercise. TSC2 phosphorylation was decreased (47%; P<0.05) in endurance-trained subjects following resistance exercise, but cycling had little effect on the phosphorylation state of this protein in either group. p70S6K phosphorylation increased in endurance- (118%; P<0.05), but not strength-trained subjects after resistance exercise, but was similar to rest in both groups after cycling. Similarly, phosphorylation of S6 protein, a substrate for p70 S6K, was increased immediately following resistance exercise in endurance- (129%; P<0.05), but not strength-trained subjects. In conclusion, a degree of "response plasticity" is conserved at opposite ends of the endurance-hypertrophic adaptation continuum. Moreover, prior training attenuates the exercise specific signaling responses involved in single mode adaptations to training.
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Abstract
The twitch interpolation technique is commonly employed to assess the completeness of skeletal muscle activation during voluntary contractions. Early applications of twitch interpolation suggested that healthy human subjects could fully activate most of the skeletal muscles to which the technique had been applied. More recently, however, highly sensitive twitch interpolation has revealed that even healthy adults routinely fail to fully activate a number of skeletal muscles despite apparently maximal effort. Unfortunately, some disagreement exists as to how the results of twitch interpolation should be employed to quantify voluntary activation. The negative linear relationship between evoked twitch force and voluntary force that has been observed by some researchers implies that voluntary activation can be quantified by scaling a single interpolated twitch to a control twitch evoked in relaxed muscle. Observations of non-linear evoked-voluntary force relationships have lead to the suggestion that the single interpolated twitch ratio can not accurately estimate voluntary activation. Instead, it has been proposed that muscle activation is better determined by extrapolating the relationship between evoked and voluntary force to provide an estimate of true maximum force. However, criticism of the single interpolated twitch ratio typically fails to take into account the reasons for the non-linearity of the evoked-voluntary force relationship. When these reasons are examined, it appears that most are even more challenging to the validity of extrapolation than they are to the linear equation. Furthermore, several factors that contribute to the observed non-linearity can be minimised or even eliminated with appropriate experimental technique. The detection of small activation deficits requires high resolution measurement of force and careful consideration of numerous experimental details such as the site of stimulation, stimulation intensity and the number of interpolated stimuli. Sensitive twitch interpolation techniques have revealed small to moderate deficits in voluntary activation during brief maximal efforts and progressively increasing activation deficits (central fatigue) during exhausting exercise. A small number of recent studies suggest that resistance training may result in improved voluntary activation of the quadriceps femoris and ankle plantarflexor muscles but not the biceps brachii. A significantly larger body of evidence indicates that voluntary activation declines as a consequence of bed-rest, joint injury and joint degeneration. Twitch interpolation has also been employed to study the mechanisms by which caffeine and pseudoephedrine enhance exercise performance.
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Abstract
AIMS Pseudoephedrine (PSE) is a readily available over-the-counter nasal decongestant which is structurally similar to amphetamine and is included on the International Olympic Committee's list of banned substances. However to date, little research has supported its putative ergogenic effect. This study investigated whether a 180 mg dose of PSE ingested 45 min prior to exercise enhanced short-term maximal exercise performance and/or altered related physiological variables. METHODS A randomised, double-blind, crossover study in 22 healthy male athletes. RESULTS Maximum torque (mean +/- s.d., n = 22) produced in an isometric knee extension exercise was 321.1+/-62.0 Nm (PSE) and 295.7+/-72.4 Nm (placebo), and peak power obtained on the 'all-out' 30 s cycle test was 1262.5+/-48.5 W (PSE) and 1228.4+/-47.1 W (placebo) (P<0.01, P<0.03, respectively). Subjects were estimated to be producing 96.9+/-2.4% of their maximal possible isometric leg extension force after PSE ingestion, but only 95.3+/-2.4% when PSE was not ingested. Bench press tasks and total work during the cycle test were not affected by the ingestion of PSE. Lung function was altered following ingestion of PSE (P<0.05) with FEV1 and FVC significantly increased (P<0.02, P<0.01, respectively) although the FEV1/FVC ratio was not altered. Heart rate was significantly elevated by the ingestion of PSE immediately following the 30 s cycle sprint (P<0.01) however, lactate concentration was not altered by the ingestion of PSE. CONCLUSIONS The administration of a 180 mg dose of PSE increased maximum torque, produced in an isometric knee extension and produced an improvement in peak power during maximal cycle performance, as well as improving lung function.
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