Dance Exposure, Individual Characteristics, and Injury Risk over Five Seasons in a Professional Ballet Company

PURPOSE

This study aimed to describe the relationships between dance exposure, dancer characteristics, and injury risk across five seasons in a professional ballet company.

METHODS

Dance exposure time and clinician-reported time-loss and medical attention injury data were prospectively collected from 118 professional dancers of The Royal Ballet between 2015/2016 and 2019/2020. Cox proportional hazards and shared frailty models were fitted to overuse and traumatic injuries; individualized robust Z-scores for 7- and 28-d accumulated exposure, and week-to-week change in exposure, age, sex, company rank, and injury history were included as time-varying covariates.

RESULTS

Across 381,710 h of exposure, 1332 medical attention and 427 time-loss injuries were observed. Positive relationships were observed between week-to-week change in exposure and overuse time-loss (+1 Z-score hazard ratio (HR), 1.27; 95% confidence interval (CI), 1.06-1.53) and medical attention injury risk (+1 Z-score HR, 1.17; 95% CI, 1.06-1.28). A negative relationship was observed between 7-d accumulated exposure and overuse medical attention injury risk (+1 Z-score HR, 0.74; 95% CI, 0.66-0.84). Overuse time-loss injury risk was greater in soloists compared with the corps de ballet (HR, 1.47; 95% CI, 1.01-2.15) and in dancers with a higher previous injury rate (+1 injury per 1000 h HR, 1.06; 95% CI, 1.02-1.10). Only age was associated with traumatic time-loss (+1-yr HR, 1.05; 95% CI, 1.01-1.09) or medical attention injury risk (+1-yr HR, 1.04; 95% CI, 1.01-1.07).

CONCLUSIONS

Professional ballet companies should implement training principles such as periodization and progression, particularly in the case of senior-ranking dancers, older dancers, and dancers with high rates of previous injury. These findings provide a basis for future prospective investigations into specific causal injury pathways.

Epidemiology and pain in elementary school-aged players: a survey of Japanese badminton players participating in the national tournament

Pain is common in athletes which should be well managed. To identify risk factors for shoulder pain, and the association between shoulder pain, lower back pain and knee pain among elementary school-aged badminton players, we conducted a cross-sectional study to collect data of the past year among 611 elementary school age (7-12 years old) badminton players belonging to the Japan Schoolchildren Badminton Federation using a questionnaire. Odds ratio (OR) and 95% confidence interval (CI) were estimated by multivariate logistic regression analysis. The overall incidence rate of shoulder injuries, lower back injuries and knee injuries was 0.38 injuries per 1000 h of badminton training. Players with training time per day > 2.5 h were 2.64 times (95% CI 1.03-6.78, p = 0.043) more likely to sustain shoulder pain than those with training time per day ≤ 2.5 h. A significant association was revealed between shoulder pain and knee pain as well as between lower back pain and knee pain as training hours per day > 2.5 h. Moreover, lower back pain was significantly associated with shoulder pain independent of training hours per day (≤ 2.5 h: p = 0.001; > 2.5 h: p < 0.001). These findings indicate that training time per day is risk factor, and shoulder pain, lower back pain and knee pain were associated with each other in elementary school-aged badminton players.

Clinical Practice Guidelines for Exertional Rhabdomyolysis: A Military Medicine Perspective

ABSTRACT

Exertional rhabdomyolysis (ER) is an uncommon condition with a paucity of evidence-based guidance for diagnosis, management, and return to duty or play. Recently, a clinical practice guideline for diagnosis and management of ER in warfighters was updated by a team of military and civilian physicians and researchers using current scientific literature and decades of experience within the military population. The revision concentrated on challenging and controversial clinical questions with applicability to providers in the military and those in the greater sports medicine community. Specific topics addressed: 1) diagnostic criteria for ER; 2) clinical decision making for outpatient versus inpatient treatment; 3) optimal strategies for inpatient management; 4) discharge criteria; 5) identification and assessment of warfighters/athletes at risk for recurrent ER; 6) an appropriate rehabilitative plan; and finally, 7) key clinical questions warranting future research.

Risk Factors for Lower-Extremity Injuries in Female Ballet Dancers: A Systematic Review

BACKGROUND

Ballet dancers have a high prevalence of injuries to the lower extremity. Many studies have investigated the relationship between dance injury and risk factors. However, risk factors for lower-extremity injury comparing recreational- and elite-level ballet dancers are scarce.

OBJECTIVE

To systematically review available original studies to assess risk factors for lower-extremity injury in female ballet dancers between recreational and elite ballet dancers.

DATA SOURCES

Five online databases [Web of Science, PubMed, OVID (Medline), EBSCO, and ProQuest] were searched systematically.

STUDY SELECTION

Included studies had an analytic study design published in the past 11 years and investigated an association between potential risk factors and lower-extremity injury in female ballet dancers.

STUDY APPRAISAL

Assessed independently by 2 reviewers using the Downs and Black (DB) criteria and Oxford Centre of Evidence-Based Medicine.

RESULTS

Seventeen studies were included. Alignment was a risk factor for lower-extremity injury in both recreational and elite ballet dancers. In elite ballet dancers, poor lumbopelvic movement control, inappropriate transversus abdominis contraction, decreased lower-extremity strength, and poor aerobic fitness were risk factors for lower-extremity injury. In recreational ballet dancers, hypermobility of the hip and ankle and longer training hours were risk factors for lower-extremity injury. Mean DB score was 15.94 (SD 1.57). The majority of studies were retrospective cohort studies or had poor follow-up, with 7 level 2b studies, 6 level 3b studies (cross-sectional), and 4 level 1b studies (prospective cohort with good follow-up).

CONCLUSIONS

Alignment was identified as a common risk factor for recreational and elite ballet dancers. Other risk factors differed between recreational ballet dancers and elite ballet dancers. Future studies are warranted to use a prospective study design, identify dance level-specific risk factors, and implement evidence-based prevention strategies.

Training and technique choices predict self-reported running injuries: An international study

OBJECTIVES

The aim of this study was to describe the self-reported injury, training, and running technique choices of regular runners in four international regions.

DESIGN AND SETTING

756 participants began an expert derived self-report online survey in Ireland, USA, Hong Kong and Australia.

PARTICIPANTS

325 participants completed the survey (age = 38 ± 10 years; weight = 68.0 ± 13.1 kg; height = 1.70 ± 0.10 m).

MAIN OUTCOME MEASURES

Descriptive statistics are reported examining injury incidence and location; shoe and orthosis choices; and training and technique practices. A backwards logistic regression was implemented to examine associations between injury and training choices.

RESULTS

68.3% reported having an injury in the last year. 81.45% of these injuries were believed to be running related. A large variation in training and footwear choices were observed for respondents. The regression (P ≤ 0.001) explained 20% of the variance in injury selection (Nagelkerke R²) and was able to identify 73% of cases accurately. Associated injury factors included competitive running, running on more than one surface, younger age, having a lower running age, and a higher proportion of running at an easy intensity.

CONCLUSIONS

The high amount of variability in runner's choices highlights the lack of consistent information being presented to them and may be the reason for the high injury incidence.

Are internal load measures associated with injuries in male adolescent Gaelic football players?

This study aimed to examine internal loads in male adolescent Gaelic footballers and their association with musculoskeletal injury. Written training diaries were completed by 97 male adolescent Gaelic footballers weekly and injuries, defined as any injury sustained during training or competition causing restricted performance or time lost from play, were assessed by a Certified Athletic Therapist. Daily load was determined for each player (session rating of perceived exertion by session duration) and summed to give weekly load. Univariate and multiple logistic regressions were conducted to determine the association with injury. Twenty-two injuries were recorded with match injuries significantly more common than training injuries. Periodic variations in weekly load and injuries were evident throughout the season. Univariate analysis identified weekly load (OR = 2.75; 95%CI = 1.00-7.59), monotony (OR = 4.17; 95%CI = 1.48-11.72) and absolute change in load (OR = 3.27; 95%CI = 1.15-9.32) greater than the team average were significant injury risk factors. Multiple logistic regression with 2-weekly and 3-weekly cumulative loads, absolute change, monotony, strain, ACWR and age as independent variables identified internal load measures (monotony, strain and absolute change) were associated with injury with high specificity (96.0%) but low sensitivity (25.0%). The findings highlight the need to monitor team and individual loads to avoid sudden week-to-week changes or excessive weekly loads. Open communication between players, parents, coaches and sports medicine clinicians enables effective load monitoring that can reduce injury risk and may subsequently minimise dropout, improve team success and overall sport enjoyment and promote life-long sports participation.

Impact of CrossFit-Related Spinal Injuries

INTRODUCTION

Exercise-related injuries (ERIs) are a common cause of nonfatal emergency department and hospital visits. CrossFit is a high-intensity workout regimen whose popularity has grown rapidly. However, ERIs due to CrossFit remained under investigated.

METHODS

All patients who presented to the main hospital at a major academic center complaining of an injury sustained performing CrossFit between June 2010 and June 2016 were identified. Injuries were classified by anatomical location (eg, knee, spine). For patients with spinal injuries, data were collected including age, sex, body mass index (BMI), CrossFit experience level, symptom duration, type of symptoms, type of clinic presentation, cause of injury, objective neurological examination findings, imaging type, number of clinic visits, and treatments prescribed.

RESULTS

Four hundred ninety-eight patients with 523 CrossFit-related injuries were identified. Spine injuries were the most common injuries identified, accounting for 20.9%. Among spine injuries, the most common location of injury was the lumbar spine (83.1%). Average symptom duration was 6.4 months ± 15.1, and radicular complaints were the most common symptom (53%). A total of 30 (32%) patients had positive findings on neurologic examination. Six patients (6.7%) required surgical intervention for treatment after failing an average of 9.66 months of conservative treatment. There was no difference in age, sex, BMI, or duration of symptoms of patients requiring surgery with those who did not.

CONCLUSIONS

CrossFit is a popular, high-intensity style workout with the potential to injure its participants. Spine injuries were the most common type of injury observed and frequently required surgical intervention.

Acute Illness in the Athlete

Athletes are susceptible to many acute illnesses that can interfere with their ability to train and compete as well as potentially affecting teammates and coaching staff. A solid understanding of the preventive measures, diagnosis, and management of such diseases is paramount in the care of an athletic population.

The Occurrence, Causes and Perceived Performance Effects of Breast Injuries in Elite Female Athletes

Female breasts are vulnerable to direct blows or frictional injuries during sport; however, little research has investigated breast injuries experienced by female athletes. This study aimed to investigate the occurrence, causes and perceived performance effects of breast injuries in elite female athletes across a wide range of sports. A custom-designed survey was distributed to female athletes aged over 18 years who were competing nationally or internationally in their chosen sport. The survey included questions about breast injuries sustained during training and competition and any perceived performance effects of these injuries. 504 elite female athletes from 46 different sports completed the survey. 36% of participants (n = 182) reported experiencing breast injuries and 21% (n = 37) perceived that their breast injury negatively affected their performance. Contact breast injuries were reported by significantly more athletes involved in contact or combat sports and by athletes with larger breasts or a higher body mass index. Frictional breast injuries were reported by significantly more older athletes or those with larger breasts. Less than 10% of participants who experienced breast injuries reported their injury to a coach or medical professional and only half used any prevention strategies. Athletes, coaches and medical professionals associated with women's sport need to be made aware of the occurrence and potential negative effects of breast injuries. It is critical to normalise conversations around breast health so that athletes can be encouraged to report and, when necessary, receive treatment for breast injuries. Further research is also required to better understand factors that affect breast injuries in sport in order to develop evidence-based breast injury prevention strategies.

Training Regimes and Recovery Monitoring Practices of Elite British Swimmers

Consistent prescriptions for event-specific training of swimmers are lacking, which points to likely differences in training practices and a potential gap between practice and scientific knowledge. This study aimed to analyze the distance-specific training load of elite swimmers, derive a consistent training sessions' description and reflect on the current recommendations for training and recovery. The individual training regimes of 18 elite British swimmers were documented by surveying four swim and two strength and conditioning (S&C) coaches. The annual and weekly training load and content were compared between swimmers competing in sprint, middle and long-distance events. Thematic analysis of the surveys was conducted to identify key codes and general dimensions and to define a unified classification of the swimming and S&C training sessions. Weekly training loads and content of the swim (ƞ² - effect size; p = 0.016, ƞ² = 0.423) and S&C (p = 0.028, ƞ² = 0.38) sessions significantly differed between the groups. Long-distance swimmers swam significantly longer distances (mean ± SD; 58.1 ± 10.2 km vs. 43.2 ± 5.3 km; p = 0.018) weekly but completed similar number of S&C sessions compared to sprinters. The annual swimming load distribution of middle-distance specialists did not differ from that of long-distance swimmers but consisted of more S&C sessions per week (4.7 ± 0.5 vs. 2.3 ± 2.3; p = 0.04). Sprinters and middle-distance swimmers swam similar distances per week and completed similar number of S&C sessions but with different proportional content. Whereas all coaches reported monitoring fatigue, only 51% indicated implementing individualized recovery protocols. We propose a consistent terminology for the description of training sessions in elite swimming to facilitate good practice exchanges. While the training prescription of elite British swimmers conforms to the scientific training principles, recommendations for recovery protocols to reduce the risk of injury and overtraining are warranted.

Going Against the Grains: Gluten-Free Diets in Patients Without Celiac Disease-Worthwhile or Not?

While the gluten-free diet (GFD) is the only known effective therapy for celiac disease, in recent years it has become increasingly popular in the USA and worldwide, with many believing it to be more "healthful" and others claiming that it has beneficial effects for health conditions, many extraintestinal, other than celiac disease. This review examines the evidence for use of the GFD in patients without celiac disease who self-report intestinal and/or extraintestinal symptoms (non-celiac gluten sensitivity), as well as for enhancement of athletic performance and treatment of autism, rheumatoid arthritis, and psychiatric disorders. Overall, the evidence for use of GFDs in conditions other than celiac disease is poor. Though non-celiac gluten sensitivity may ultimately emerge as a biomarker-defined condition, a large proportion of patients with apparent non-celiac gluten sensitivity have, after careful investigation, an alternative diagnosis. In light of this, and coupled with the potential physical and psychological harms associated with the avoidance of gluten, initiating a GFD should not be encouraged for people who have these other conditions or are seeking physical/athletic enhancement.

You're the Flight Surgeon

Nussbaum L. You're the flight surgeon: loss of consciousness while exercising. Aerosp Med Hum Perform. 2018; 89(8):760-762.

Musculoskeletal training injury prevention in the U.S. Army: Evolution of the science and the public health approach

Injuries cause more morbidity among soldiers in the U.S. Army than any other health condition. Over two-thirds of U.S. soldiers' injuries occur gradually from cumulative micro-traumatic damage to the musculoskeletal system as a result of physical training activities. Paradoxically, the very physical training activities required to improve soldier performance also result in injury. Determining the amounts and types of physical training that maximize performance while minimizing injuries requires scientific evidence. This evidence must be incorporated into a framework that ensures scientific gaps are addressed and prevention efforts are evaluated. The five-step public health approach has proven to be an effective construct for Army public health to organize and build an injury prevention program. Steps include: 1) surveillance to define the magnitude of the problem, 2) research and field investigations to identify causes and risk factors, 3) intervention trials and systematic reviews to determine what works to address leading risk factors, 4) program and policy implementation to execute prevention, and 5) program evaluation to assess effectiveness. Dissemination is also needed to ensure availability of scientific lessons learned. Although the steps may not be conducted in order, the capability to perform each step is necessary to sustain a successful program and make progress toward injury control and prevention. As with many U.S. public health successes (e.g., seatbelts, smoking cessation), the full process can take decades. As described in this paper, the U.S. Army uses the public health approach to assure that, as the science evolves, it is translated into effective prevention.

Aerobic training performed at ventilatory threshold improves liver enzymes and lipid profile related to non-alcoholic fatty liver disease in adolescents with obesity

BACKGROUND

Despite the positive effects of high-intensity training on weight management and health-related outcomes, it is postulated that high-intensity training may also induce oxidative stress, increasing hepatic damage.

AIM

The aim of this study was to compare the effects of low versus high-intensity training on biomarkers related to non-alcoholic fatty liver disease (NAFLD) in adolescents with obesity.

METHODS

For this study 107 adolescents (15 ± 1 years) with obesity (BMI = 34.7 ± 4.1 kg/m²) were randomized into High-Intensity Training (HIT, n = 31), Low-Intensity Training (LIT, n = 31) or Control Group (CG, n = 45). Adolescents from HIT and LIT received nutritional, psychological and clinical counseling. Blood lipids, Castelli risk index, glucose, insulin and hepatic enzymes were measured at baseline and after 12 weeks.

RESULTS

Castelli risk index 1 was reduced in all groups ( p < 0.001) with moderate effect size ( d) for HIT ( d = 0.62) and LIT ( d = 0.66). Castelli risk index 2 also decreased ( p < 0.001 for all groups; HIT d = 0.65; LIT d = 0.79). High-density lipoprotein increased in all groups ( d = 0.25 and d = 0.18 in HIT and LIT), while alanine aminotransferase tended to reduce ( p = 0.062) in HIT ( d = 0.34) and LIT ( d = 0.73) and aspartate aminotransferase decreased ( p = 0.024) in both HIT ( d = 0.24) and LIT ( d = 0.45). There were no changes in glucose, insulin and insulin resistance.

CONCLUSION

Both high and low-intensity training improved biomarkers related to NAFLD. Thus, high-intensity training can be a safe and effective alternative to prevent and treat NAFLD in adolescents with obesity.

Impact of acute versus repetitive moderate intensity endurance exercise on kidney injury markers

Exercise may lead to kidney injury through several mechanisms. Urinary Kidney Injury Molecule-1 (uKIM1) and Neutrophil Gelatinase-Associated Lipocalin (uNGAL) are known biomarkers for acute kidney injury, but their response to repetitive exercise remains unknown. We examined the effects of a single versus repetitive bouts of exercise on markers for kidney injury in a middle-aged population. Sixty subjects (aged 29-78 years, 50% male) were included and walked 30, 40 or 50 km for three consecutive days. At baseline and after exercise day 1 and 3, a urine sample was collected to determine uNGAL and uKIM1. Furthermore, urinary cystatin C, creatinine, and osmolality were used to correct for dehydration-related changes in urinary concentration. Baseline uNGAL was 9.2 (5.2-14.7) ng/mL and increased to 20.7 (11.0-37.2) ng/mL and 14.2(8.0-26.3) ng/mL after day 1 and day 3, respectively, (P ≤ 0.001). Baseline uKIM1 concentration was 2.6 (1.4-6.0) ng/mL and increased to 5.2 (2.4-9.1) ng/mL (P = 0.002) after day 1, whereas uKIM1 was not different from baseline at day 3 (2.9 [1.4-6.4] ng/mL (P = 0.52)). Furthermore, both uNGAL and uKIM1 levels were higher after day 1 compared to day 3 (P < 0.01). When corrected for urinary cystatin C, creatinine, and osmolality, uNGAL demonstrated a similar response compared to the uncorrected data, whereas differences in uKIM1 between baseline, day 1 and day 3 (Ptime = 0.63) were no longer observed for cystatin C and creatinine corrected data. A single bout of prolonged exercise significantly increased uNGAL concentration, whereas no changes in uKIM1 were found. Repetitive bouts of exercise show that there is no cumulative effect of kidney injury markers.

Thyroid hormones and commonly cited symptoms of overtraining in collegiate female endurance runners

PURPOSE

Overtraining syndrome (OTS) is reported in endurance sports. Thyroid hormones (TH) regulate metabolism, mood, and energy production, and may play a role in OTS of endurance athletes. The purpose of this study was to investigate relationships in TH and symptoms of OTS in track and field endurance runners (ER).

METHODS

Sixteen female track and field middle distance (MD; n = 9; age: 20.2 ± 1.5 years; ht: 167.86 ± 5.04 cm; body-mass: 57.97 ± 5.05 kg; VO_2MAX: 53.62 ± 6.04 ml/kg/min) and long distance (LD; n = 7; age: 20.5 ± 1.5 years; ht: 162.48 ± 6.11 cm; body-mass: 56.15 ± 5.99 kg; VO_2MAX: 61.94 ± 3.29 ml/kg/min) ER participated in this descriptive study (15-weeks). Thyroid-stimulating hormone (TSH), triiodothyronine (T ₃), and thyroxine (T ₄), were collected at pre-(PRE) and post-season (POST). A fatigue scale was administered weekly, and percent change (PΔ) in race time (season best vs. championship performance) was calculated. Wilcoxon-sign ranked tests and Spearman's rho correlations were used to determine changes and relationships between TH and performance.

RESULTS

TSH, T ₃ and T ₄ did not change from PRE to POST. The percent change (PΔ) in T ₃ from PRE to POST was correlated with running performance at the end of the season (ρ = - 0.70, p = 0.036). Fatigue at week 12 correlated with running performance at the end of the season (ρ = - 0.74, p = 0.004).

CONCLUSION

TH may be valuable in assessing the overall training state of ER. TH concentrations change too slowly to be a frequent marker of monitoring OTS, but are related to markers of decreased performance. Monitoring dietary intake, and fatigue may be predictive markers to assess OTS and training status of female ER.

Recovery following a marathon: a comparison of cold water immersion, whole body cryotherapy and a placebo control

PURPOSE

Cryotherapy is an increasingly popular recovery strategy used in an attempt to attenuate the negative impact of strenuous physical activity on subsequent exercise. Therefore, this study aimed to assess the effects of whole body cryotherapy (WBC) and cold water immersion (CWI) on markers of recovery following a marathon.

METHODS

Thirty-one endurance trained males completed a marathon. Participants were randomly assigned to a CWI, WBC or placebo group. Perceptions of muscle soreness, training stress and markers of muscle function were recorded before the marathon and at 24 and 48 h post exercise. Blood samples were taken at baseline, post intervention and 24 and 48 h post intervention to assess inflammation and muscle damage.

RESULTS

WBC had a harmful effect on muscle function compared to CWI post marathon. WBC positively influenced perceptions of training stress compared to CWI. With the exception of C-reactive protein (CRP) at 24 and 48 h, neither cryotherapy intervention positively influenced blood borne markers of inflammation or structural damage compared to placebo.

CONCLUSION

The findings show WBC has a negative impact on muscle function, perceptions of soreness and a number of blood parameters compared to CWI, contradicting the suggestion that WBC may be a superior recovery strategy. Further, cryotherapy is no more effective than a placebo intervention at improving functional recovery or perceptions of training stress following a marathon. These findings lend further evidence to suggest that treatment belief and the placebo effect may be largely responsible for the beneficial effects of cryotherapy on recovery following a marathon.

Exercise and gastrointestinal symptoms: running-induced changes in intestinal permeability and markers of gastrointestinal function in asymptomatic and symptomatic runners

PURPOSE

Athletes frequently experience gastrointestinal (GI) symptoms during training and competition. Although the prevalence of exercise-induced GI symptoms is high, the mechanisms leading to GI distress during exercise are not fully understood. The aim of this study was to identify running-induced changes in intestinal permeability and markers of GI function and investigate their association with gastrointestinal symptoms.

METHODS

We recruited 17 active runners who we allocated as either asymptomatic or symptomatic based on their history of experiencing GI symptoms during running. The participants took part in a running test where they were asked to run for 90 min at 80% of their best 10 km race speed. Intestinal permeability was measured at baseline and after the running test. Levels of serum intestinal fatty acid-binding protein (I-FABP), zonulin, bacterial lipopolysaccharide (LPS), and fecal calprotectin were also measured at baseline and after the running test.

RESULTS

Running induced a significant increase in intestinal permeability and serum I-FABP concentration but there were no differences between asymptomatic and symptomatic runners. Serum LPS activity did not change from baseline following the running test but the symptomatic group exhibited higher LPS activity at baseline compared to the asymptomatic runners.

CONCLUSIONS

Running for 90 min at a challenging pace causes small intestinal damage and increases intestinal permeability. However, these alterations in GI function do not appear to correlate with the development of GI symptoms during running.

Optimizing Musculoskeletal Performance Through Injury Prevention

Musculoskeletal injuries (MSK-Is) are ubiquitous throughout the Special Operations Forces (SOF) because of the physical demands of executing missions and carrying heavy loads. Preventing MSK-I has been a priority among SOF but is especially challenging because most MSK-Is are chronic or recurring. For many SOF, musculoskeletal issues and MSK pain are just part of doing their job. Ways to focus, target, and integrate injury prevention efforts across the continuum of training, active duty and SOF status are critical because MSK-Is are a significant barrier to human performance optimization. In this article, we describe how to incorporate these efforts at all levels of training. The need for improving valid, objective, fit-for-full-duty metrics after injury and sharing such information continuously with SOF is discussed. Last, strategies for engaging all levels to begin a culture shift away from the acceptance of MSK-I and pain as a way of life toward embracing MSK-I prevention as a regular part of everyday training are presented.

NCAA strength and conditioning coach demographics, current practice trends and common injuries of athletes during strength and conditioning sessions

BACKGROUND

NCAA strength and conditioning coaches are responsible for the day-to-day conditioning and strength training of collegiate athletes. NCAA regulations will likely require all strength and conditioning coaches to have a strength and conditioning certification. NCAA strength and conditioning coaches have varied philosophies on exercise programming based on educational background. The study aims to further evaluate the backgrounds and exercise philosophies of NCAA strength and conditioning coaches.

METHODS

A survey (Survey Monkey®, Palo Alto, CA, USA) was distributed to NCAA strength and conditioning professionals to evaluate their education background, current practice trends, use of specific equipment and footwear, and what injuries occurred during sessions.

RESULTS

Of the 208 survey participants, 77.9% were male with an average age of 34.5±9.1 years old. An exercise-related bachelor's degree was held by 80.4% and an exercise-related master's degree by 72.4%. Over 89% had a strength and conditioning certification. Having a master's, bachelor's, or type strength and conditioning certification had no difference in 1-repetition maximal practice with athletes. Lower extremity injuries made up the highest percentage (58.9%) of injuries seen by NCAA Strength and Conditioning Coaches than lumbar spine injuries (16.7%). The five most common injuries reported during workouts were lumbar strain (N.=431, 14.7%), hamstring strain (N.=332, 11.3%), ankle sprain (N.=299, 10.2%), patellar tendonitis (N.=232, 7.9%), and shin splints (N.=226, 7.7%).

CONCLUSIONS

Collegiate education and certifications have impact on practice patterns of strength and conditioning coaches in the NCAA.

Effect of Caloric Restriction or Aerobic Exercise Training on Peak Oxygen Consumption and Quality of Life in Obese Older Patients With Heart Failure With Preserved Ejection Fraction: A Randomized Clinical Trial

IMPORTANCE

More than 80% of patients with heart failure with preserved ejection fraction (HFPEF), the most common form of heart failure among older persons, are overweight or obese. Exercise intolerance is the primary symptom of chronic HFPEF and a major determinant of reduced quality of life (QOL).

OBJECTIVE

To determine whether caloric restriction (diet) or aerobic exercise training (exercise) improves exercise capacity and QOL in obese older patients with HFPEF.

DESIGN, SETTING, AND PARTICIPANTS

Randomized, attention-controlled, 2 × 2 factorial trial conducted from February 2009 through November 2014 in an urban academic medical center. Of 577 initially screened participants, 100 older obese participants (mean [SD]: age, 67 years [5]; body mass index, 39.3 [5.6]) with chronic, stable HFPEF were enrolled (366 excluded by inclusion and exclusion criteria, 31 for other reasons, and 80 declined participation).

INTERVENTIONS

Twenty weeks of diet, exercise, or both; attention control consisted of telephone calls every 2 weeks.

MAIN OUTCOMES AND MEASURES

Exercise capacity measured as peak oxygen consumption (V̇O2, mL/kg/min; co-primary outcome) and QOL measured by the Minnesota Living with Heart Failure (MLHF) Questionnaire (score range: 0-105, higher scores indicate worse heart failure-related QOL; co-primary outcome).

RESULTS

Of the 100 enrolled participants, 26 participants were randomized to exercise; 24 to diet; 25 to exercise + diet; 25 to control. Of these, 92 participants completed the trial. Exercise attendance was 84% (SD, 14%) and diet adherence was 99% (SD, 1%). By main effects analysis, peak V̇O2 was increased significantly by both interventions: exercise, 1.2 mL/kg body mass/min (95% CI, 0.7 to 1.7), P < .001; diet, 1.3 mL/kg body mass/min (95% CI, 0.8 to 1.8), P < .001. The combination of exercise + diet was additive (complementary) for peak V̇O2 (joint effect, 2.5 mL/kg/min). There was no statistically significant change in MLHF total score with exercise and with diet (main effect: exercise, -1 unit [95% CI, -8 to 5], P = .70; diet, -6 units [95% CI, -12 to 1], P = .08). The change in peak V̇O2 was positively correlated with the change in percent lean body mass (r = 0.32; P = .003) and the change in thigh muscle:intermuscular fat ratio (r = 0.27; P = .02). There were no study-related serious adverse events. Body weight decreased by 7% (7 kg [SD, 1]) in the diet group, 3% (4 kg [SD, 1]) in the exercise group, 10% (11 kg [SD, 1] in the exercise + diet group, and 1% (1 kg [SD, 1]) in the control group.

CONCLUSIONS AND RELEVANCE

Among obese older patients with clinically stable HFPEF, caloric restriction or aerobic exercise training increased peak V̇O2, and the effects may be additive. Neither intervention had a significant effect on quality of life as measured by the MLHF Questionnaire.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00959660.

Low serum 25-hydroxyvitamin D is associated with increased risk of stress fracture during Royal Marine recruit training

The aim of this study was to investigate vitamin D status and stress fracture risk during Royal Marine military training. Poor vitamin D status was associated with an increased risk of stress fracture. Vitamin D supplementation may help to reduce stress fracture risk in male military recruits with low vitamin D status.

INTRODUCTION

Stress fracture is a common overuse injury in military recruits, including Royal Marine (RM) training in the UK. RM training is recognised as one of the most arduous basic training programmes in the world. Associations have been reported between serum 25-hydroxyvitamin D (25(OH)D) and risk of stress fracture, but the threshold of 25(OH)D for this effect remains unclear. We aimed to determine if serum 25(OH)D concentrations were associated with stress fracture risk during RM training.

METHODS

We prospectively followed 1082 RM recruits (males aged 16-32 years) through the 32-week RM training programme. Troops started training between September and July. Height, body weight and aerobic fitness were assessed at week 1. Venous blood samples were drawn at weeks 1, 15 and 32. Serum samples were analysed for 25(OH)D and parathyroid hormone (PTH).

RESULTS

Seventy-eight recruits (7.2 %) suffered a total of 92 stress fractures. Recruits with a baseline serum 25(OH)D concentration below 50 nmol L(-1) had a higher incidence of stress fracture than recruits with 25(OH)D concentration above this threshold (χ(2) (1) = 3.564, p = 0.042; odds ratio 1.6 (95 % confidence interval (CI) 1.0-2.6)). Baseline serum 25(OH)D varied from 47.0 ± 23.7 nmol L(-1) in February, to 97.3 ± 24.6 nmol L(-1) in July (overall mean 69.2 ± 29.2 nmol L(-1), n = 1016). There were weak inverse correlations between serum 25(OH)D and PTH concentrations at week 15 (r = -0.209, p < 0.001) and week 32 (r = -0.214, p < 0.001), but not at baseline.

CONCLUSION

Baseline serum 25(OH)D concentration below 50 nmol L(-1) was associated with an increased risk of stress fracture. Further studies into the effects of vitamin D supplementation on stress fracture risk are certainly warranted.

Sonographic inferior vena cava measurements to assess hydration status in college football players during preseason camp

OBJECTIVES

The purpose of this study was to determine whether sonographic measurement of the inferior vena cava (IVC) in college football players during preseason camp is a reliable way to detect and monitor dehydration. Our primary hypothesis was that IVC diameter measurements, the postpractice caval index, and expiratory diameter were significantly related to percent weight loss after a preseason football practice.

METHODS

A prospective cohort sample of Division I intercollegiate football players in preseason training camp was recruited before practice. All football players on the active roster who were at least 18 years of age were eligible to participate in the study. Sonographic IVC measurements were obtained in the long axis using either the subcostal or subxiphoid approach during inspiration and expiration both before and after an approximately 3-hour practice with moderate to high levels of exertion at high ambient temperatures. Player weights were recorded in the locker room before and after practice.

RESULTS

A total of 27 prepractice and postpractice sonographic measurements were obtained. The postpractice expiratory IVC diameter was significantly related to percent weight loss after practice (R(2) = 0.153; P = .042), with the IVC diameter being significantly inversely correlated with percent weight loss; the regression coefficient was -1.07 (95% confidence interval, -2.09 to -0.04). There was no statistically significant relationship between percent weight loss and the postpractice caval index; the regression coefficient was 0.245 (95% confidence interval, -0.10 to 0.59; R(2) = 0.078; P = .16).

CONCLUSIONS

The postpractice expiratory IVC diameter was significantly related to percent weight loss after practice, whereas the caval index was not found to correlate with weight loss.

Extreme Conditioning Programs: Potential Benefits and Potential Risks

CrossFit, Insanity, Gym Jones, and P90X are examples of extreme conditioning programs (ECPs). ECPs typically involve high-volume and high-intensity physical activities with short rest periods between movements and use of multiple joint exercises. Data on changes in fitness with ECPs are limited to CrossFit investigations that demonstrated improvements in muscle strength, muscular endurance, aerobic fitness, and body composition. However, no study has directly compared CrossFit or other ECPs to other more traditional forms of aerobic and resistance training within the same investigation. These direct comparisons are needed to more adequately evaluate the effectiveness of ECPs. Until these studies emerge, the comparisons with available literature suggest that improvements in CrossFit, in terms of muscular endurance (push-ups, sit-ups), strength, and aerobic capacity, appear to be similar to those seen in more traditional training programs. Investigations of injuries in ECPs are limited to two observational studies that suggest that the overall injury rate is similar to that seen in other exercise programs. Several cases of rhabdomyolysis and cervical carotid artery dissections have been reported during CrossFit training. The symptoms, diagnosis, and treatment of these are reviewed here. Until more data on ECPs emerge, physical training should be aligned with US Army doctrine. If ECPs are included in exercise programs, trainers should (1) have appropriate training certifications, (2) inspect exercise equipment regularly to assure safety, (3) introduce ECPs to new participants, (4) ensure medical clearance of Soldiers with special health problems before participation in ECPs, (4) tailor ECPs to the individual Soldier, (5) adjust rest periods to optimize recovery and reduce fatigue, (6) monitor Soldiers for signs of overtraining, rhabdomyolysis, and other problems, and (7) coordinate exercise programs with other unit training activities to eliminate redundant activities and minimize the risk of overuse injuries.

The impact of neuromuscular electrical stimulation on recovery after intensive, muscle damaging, maximal speed training in professional team sports players

OBJECTIVES

During congested fixture periods in team sports, limited recovery time and increased travel hinder the implementation of many recovery strategies; thus alternative methods are required. We examined the impact of a neuromuscular electrical stimulation device on 24-h recovery from an intensive training session in professional players.

DESIGN

Twenty-eight professional rugby and football academy players completed this randomised and counter-balanced study, on 2 occasions, separated by 7 days.

METHODS

After baseline perceived soreness, blood (lactate and creatine kinase) and saliva (testosterone and cortisol) samples were collected, players completed a standardised warm-up and baseline countermovement jumps (jump height). Players then completed 60 m × 50 m maximal sprints, with 5 min recovery between efforts. After completing the sprint session, players wore a neuromuscular electrical stimulation device or remained in normal attire (CON) for 8 h. All measures were repeated immediately, 2 and 24-h post-sprint.

RESULTS

Player jump height was reduced from baseline at all time points under both conditions; however, at 24-h neuromuscular electrical stimulation was significantly more recovered (mean±SD; neuromuscular electrical stimulation -3.2±3.2 vs. CON -7.2±3.7%; P<0.001). Creatine kinase concentrations increased at all time points under both conditions, but at 24-h was lower under neuromuscular electrical stimulation (P<0.001). At 24-h, perceived soreness was significantly lower under neuromuscular electrical stimulation, when compared to CON (P=0.02). There was no effect of condition on blood lactate, or saliva testosterone and cortisol responses (P>0.05).

CONCLUSIONS

Neuromuscular electrical stimulation improves recovery from intensive training in professional team sports players. This strategy offers an easily applied recovery strategy which may have particular application during sleep and travel.

Training-related risk factors in the etiology of overuse injuries in endurance sports

AIM

The purpose of this study was to clarify training-related risk factors for overuse injuries.

METHODS

This was twelve-month retrospective study which was done by self-reported postal questionnaire. The study group consisted of 446 men and women top-level Finnish athletes representing three different endurance sports (cross-country skiing, swimming, long-distance running) between the ages of 15-35. Self-reported anthropometric and training-related variables (such as starting age of training, years of active training, hours trained yearly, competition hours and weekly resting days) and occurrence of overuse injuries.

RESULTS

Athletes with less than 2 rest days per week during the training season had 5.2-fold risk (95% confidence intervals [CI] 1.89-14.06, P=0.001) for an overuse injury, and athletes who trained more than 700 hours during a year had 2.1-fold risk (95% CI 1.21-3.61, P=0.008) for an overuse injury compared to the others. Athletes who reported a tendon injury were on average two years older than athletes without such an injury (P<0.001).

CONCLUSION

We found that low number of recovery days and a high amount of training are training-related risk factors for overuse injuries in top-level endurance athletes. The higher number of tendon overuse injuries in older than younger athletes may indicate that age-related degeneration plays an important role in the etiology of tendon injuries. These findings should be taken into account when planning exercise programs for endurance athletes.

Extreme conditioning programs and injury risk in a US Army Brigade Combat Team

CONTEXT

Brigades and battalions throughout the US Army are currently implementing a variety of exercise and conditioning programs with greater focus on preparation for mission-specific tasks. An Army physical therapy clinic working with a light infantry brigade developed the Advanced Tactical Athlete Conditioning (ATAC) program. The ATAC program is a unique physical training program consisting of high-intensity aquatic exercises, tactical agility circuits, combat core conditioning, and interval speed training. Along with ATAC, battalions have also incorporated components of fitness programs such as the Ranger Athlete Warrior program and CrossFit (Crossfit, Inc, Santa Monica, CA) an extreme conditioning program (ECP).

OBJECTIVE

To determine if these new programs (ATAC, ECP) had an effect on injury rates and physical fitness.

DESIGN

Surveys were administered to collect personal characteristics, tobacco use, personal physical fitness training, Army physical fitness test results, and self-reported injuries. Medical record injury data were obtained 6 months before and 6 months after the implementation of the new program. Predictors of injury risk were assessed using multivariate logistic regression. Odds ratios (OR) and 95% confidence intervals (CI) were reported.

RESULTS

Injury incidence among Soldiers increased 12% for overall injuries and 16% for overuse injuries after the implementation of the ATAC/ECPs. However, injury incidence among Soldiers not participating in ATAC/ECPs also increased 14% for overall injuries and 10% for overuse injuries. Risk factors associated with higher injury risk for Soldiers participating in ATAC/ECPs included: greater mileage run per week during unit physical training (OR (>16 miles per week÷≤7 miles per week)=2.24, 95% CI, 1.33-3.80); higher body mass index (BMI) (OR (BMI 25-29.9÷BMI<25)=1.77, 95% CI, 1.29-2.44), (OR (BMI =30÷BMI<25)=2.72, 95% CI, 1.67-4.43); cigarette use (OR (smoker÷nonsmoker)=1.80, 95% CI, 1.34-2.42); poor performance on the 2-mile run during the Army Physical Fitness Test (APFT) (OR (=15.51 minutes÷≤13.52 minutes)=1.76, 95% CI, 1.13-2.74); Injury risk was lower for those reporting resistance training, (OR (<1 time per week÷none)=0.53, 95% CI, 0.31-0.92), (OR (1-2 times per week÷none)=0.50, 95% CI, 0.29-0.84), (OR (≥3 times per week÷none)=0.45, 95% CI, 0.24-0.85).

CONCLUSIONS

Given that Soldiers participating in ATAC/ECPs showed similar changes in injury rates compared to Soldiers not participating in ATAC/ECPs, no recommendation can be made for or against implementation of ATAC/ECPs.

Walking kinematics and kinetics following eccentric exercise-induced muscle damage

The goal of this investigation was to investigate how walking patterns are affected following muscle-damaging exercise by quantifying both lower limb kinematics and kinetics. Fifteen young women conducted a maximal isokinetic eccentric exercise (EE) muscle damage protocol (5×15) of the knee extensors and flexors of both legs at 60°/s. Three-dimensional motion data and ground reaction forces (GRFs) were collected 24h pre-EE while the participants walked at their preferred self-selected walking speed (SWS). Participants were asked to perform two gait conditions 48h post-EE. The first condition (COND1) was to walk at their own speed and the second condition (COND2) to maintain the SWS (±5%) they had 24h pre-EE. Walking speed during COND1 was significantly lower compared to pre-exercise values. When walking speed was controlled during COND2, significant effects of muscle damage were noticed, among other variables, for stride frequency, loading rate, lateral and vertical GRFs, as well as for specific knee kinematics and kinetics. These findings provide new insights into how walking patterns are adapted to compensate for the impaired function of the knee musculature following muscle damage. The importance to distinguish the findings caused by muscle damage from those exhibited in response to changes in stride frequency is highlighted.