Michael S. Koehle

Alpine Ski Injuries and Their Prevention

AbstractAlpine skiing is a popular sport with significant risk of injury. Since the 1970s, injury rates have dropped from approximately 5 to 8 per 1000 skier-days to about 2 to 3 per 1000 skier-days. The nature of the injuries has also been transformed over the same period. Lower leg injuries are becoming less common while the incidence of knee sprains and upper extremity injuries is becoming more common. Much of this change can be attributed to advancements in binding technology, which effectively reduces lower leg injury, but does not adequately address the issue of knee sprains. Along with design, binding adjustment and maintenance are important preventative factors. Poorly adjusted bindings have been correlated with increased injury rates. Upper extremity injuries constitute approximately one-third of skiing injuries, with ulnar collateral ligament sprains and shoulder injuries being the most common. Strategies to prevent these include proper poling technique and avoidance of non-detachable ski pole retention devices. Spinal injuries in skiers have been traditionally much less common than in snowboarders, but this disparity is likely to diminish with the recent trend of incorporating snowboarding moves into skiing. Strategies to help reduce these injuries include promoting the development of terrain parks and focussing on proper technique during such moves. Head injuries have been increasing in incidence over recent decades and account for more than half of skiing-related deaths. The issue of ski helmets remains controversial while evidence for their efficacy remains under debate. There is no evidence to demonstrate that traditional ski instruction reduces injury frequency. More specific programmes focussed on injury prevention techniques are effective. The question of pre-season conditioning to prevent injuries needs further research to demonstrate efficacy.

Pulmonary Oedema of Immersion

AbstractAcute pulmonary oedema has been described in individuals participating in three aquatic activities: (i) scuba diving; (ii) breath-hold diving; and (iii) endurance swimming. In this review, 60 published cases have been compiled for comparison. Variables considered included: age; past medical history; activity; water depth, type (salt or fresh) and temperature; clinical presentation; investigations; management; and outcome. From these data, we conclude that a similar phenomenon is occurring among scuba, breath-hold divers and swimmers. The pathophysiology is likely a pulmonary overperfusion mechanism. High pulmonary capillary pressures lead to extravasation of fluid into the interstitium. This overperfusion is caused by the increase in ambient pressure, peripheral vasoconstriction from ambient cold, and increased pulmonary blood flow resulting from exercise. Affected individuals are typically healthy males and females. Older individuals may be at higher risk. The most common symptoms are cough and dyspnoea, with haemoptysis also a frequent occurrence. Chest pain has never been reported. Radiography is the investigation of choice, demonstrating typical findings for pulmonary oedema. Management is supportive, with oxygen the mainstay of treatment. Cases usually resolve within 24 hours. In some cases, diuretics have been used, but there are no data as to their efficacy. Nifedipine has been used to prevent recurrence, but there is only anecdotal evidence to support its use.

Tarsal navicular stress injury : Long-term outcome and clinicoradiological correlation using both computed tomography and magnetic resonance imaging

Background Tarsal navicular stress fracture is a condition that has curtailed many athletic careers. Management protocols remain varied and somewhat controversial. Hypotheses (1) Clinical practice does not mirror the recommendations reported from previous case series. (2) Clinical outcome is poor when navicular stress fracture is managed in a variety of ways. (3) Imaging does not correlate strongly with clinical status at long-term follow-up after navicular stress fracture. Study Design Case series (prognosis); Level of evidence, 4. Methods From a computer registry, we identified patients who had attended a university sports medicine center between 1996 and 2002 and whose final diagnosis was navicular stress fracture (n = 11) or navicular stress reaction (n = 9). All patients had provided demographic and clinical data at their original evaluation, and all had undergone bone scans and computed tomographic imaging. These data were extracted by chart review. Follow-up clinical and imaging assessments took place a median of 3.7 years later (range, 1-15.7 years). At these assessments, we administered a questionnaire, performed a structured physician examination (blinded to other data), scanned both feet with computed tomography, and obtained magnetic resonance images of the affected foot. Results Only 2 of 11 patients (18%) with navicular stress fractures received the literature-recommended treatment of at least 6 weeks’ nonweightbearing cast immobilization. Of these 11 patients, only 6 (55%) returned to sports at their previous level. Only 3 patients with navicular stress fractures regained normal imaging appearance at follow-up. Pain score, stiffness, sporting success, current sporting involvement, and recurrence/time to recurrence were not statistically associated with computed tomographic or magnetic resonance imaging parameters. Of 9 patients with navicular stress reactions, 7 developed clinical and radiological features of navicular stress fracture, but 6 of 9 patients (67%) returned successfully to sports. Conclusions Contemporary management of navicular stress fracture differs from that recommended in the literature. This stress fracture prevented almost half of the participants in this study from returning to sports at their previous level. Imaging parameters do not correlate with the clinical assessment of a patient at long-term follow-up of navicular stress fracture.

The Health Effects of Exercising in Air Pollution

The health benefits of exercise are well known. Many of the most accessible forms of exercise, such as walking, cycling, and running often occur outdoors. This means that exercising outdoors may increase exposure to urban air pollution. Regular exercise plays a key role in improving some of the physiologic mechanisms and health outcomes that air pollution exposure may exacerbate. This problem presents an interesting challenge of balancing the beneficial effects of exercise along with the detrimental effects of air pollution upon health. This article summarizes the pulmonary, cardiovascular, cognitive, and systemic health effects of exposure to particulate matter, ozone, and carbon monoxide during exercise. It also summarizes how air pollution exposure affects maximal oxygen consumption and exercise performance. This article highlights ways in which exercisers could mitigate the adverse health effects of air pollution exposure during exercise and draws attention to the potential importance of land use planning in selecting exercise facilities.

Evidence for a Genetic Basis for Altitude Illness: 2010 Update

Altitude illness refers to a group of environmentally mediated pathophysiologies. Many people will suffer acute mountain sickness shortly after rapidly ascending to a moderately hypoxic environment, and an unfortunate few will develop potentially fatal conditions such as high altitude pulmonary edema or high altitude cerebral edema. Some individuals seem to be predisposed to developing altitude illness, suggesting an innate contribution to susceptibility. The implication that there are altitude-sensitive and altitude-tolerant individuals has stimulated much research into the contribution of a genetic background to the efficacy of altitude acclimatization. Although the effect of altitude attained and rate of ascent on the etiology of altitude illness is well known, there are only tantalizing, but rapidly accumulating, clues to the genes that may be involved. In 2006, we reviewed what was then known about the genetics of altitude illness. This article updates that review and attempts to tabulate all the available genetic data pertaining to these conditions. To date, 58 genes have been investigated for a role in altitude illness. Of these, 17 have shown some association with the susceptibility to, or the severity of, these conditions, although in many cases the effect size is small or variable. Caution is recommended when evaluating the genes for which no association was detected, because a number of the investigations reviewed in this article were insufficiently powered to detect small effects. No study has demonstrated a clear-cut altitude illness gene, but the accumulating data are consistent with a polygenic condition with a strong environmental component. The genes that have shown an association affect a variety of biological pathways, suggesting that either multiple systems are involved in altitude pathophysiology or that gene-gene interactions play a role. Although numerous studies have been performed to investigate specific genes, few have looked for evidence of heritability or familial transmission, or for epidemiological patterns that would be consistent with genetically influenced conditions. Future trends, such as genome-wide association studies and epigenetic analysis, should lead to enhanced understanding of the complex interactions within the genome and between the genome and hypoxic environments that contribute to an individuals capacity to acclimatize rapidly and effectively to altitude.

Oximetry, heart rate variability, and the diagnosis of mild-to-moderate acute mountain sickness.

The clinical evaluation of acute mountain sickness (AMS) is often performed in remote settings with minimal equipment. The purpose of this study was to examine the utility of heart rate variability and other cardiovascular parameters in a high-altitude clinical setting. Forty-one participants were recruited from the patient population of the clinic, and from festivalgoers [those who attended the Janai Purnima festival held at Lake Gosainkunda (4380 m) in Langtang, Nepal] in the vicinity of the clinic. Twenty-one participants were diagnosed with AMS; remaining participants were free from altitude illness. Heart rate variability (both time and frequency domain measures), arterial oxygen saturation (SpO2), blood pressure and Lake Louise Score were evaluated in all the participants. Oxygen saturation and diastolic blood pressure were negatively and positively correlated with Lake Louise Score, respectively. Receiver operating characteristic analysis indicated that an SpO2 of 86% or greater was associated with a very low likelihood of AMS at this altitude. No heart rate variability parameters were different in the AMS group as compared with the control group. In conclusion, in patients with SpO2 of 86% or more at 4380 m or higher, the likelihood of AMS is low. Diastolic blood pressure correlated with AMS severity, whereas heart rate variability was not useful in the diagnosis of AMS.

Normative data for the balance error scoring system: Implications for brain injury evaluations

Primary objective: Patients who sustain traumatic brain injuries can experience temporary or permanent deficits in static or dynamic balance. The Balance Error Scoring System (BESS) is a brief, easily-administered test of static balance that recently has been recommended for use with military personnel who do not recover rapidly from a mild traumatic brain injury. However, the test lacks normative reference values for healthy adults, which greatly limits its clinical usefulness. The purpose of this study is to provide normative data for healthy men and women across the lifespan. Methods: Community-dwelling adults (n= 589) between the ages of 20–69 (M= 49.75, SD = 10.81) were administered the BESS. They did not have significant medical, neurological or lower extremity problems that might have an adverse effect on balance. Results: There was no relation between BESS and height and a very small correlation between BESS and weight. There was a small correlation between BESS and waist girth and body mass index. BESS performance was similar in men and women. BESS scores were consistent across the age groups until the 50s, when they worsened. Normative reference values stratified by age groups are presented. Conclusions: These normative data provide a frame of reference for interpreting BESS performance in civilians and military personnel who sustain traumatic brain injuries and adults with diverse neurological problems.

Acute hypoxic ventilatory response and exercise-induced arterial hypoxemia in men and women

Recent studies claim a higher prevalence of exercise-induced arterial hypoxemia (EIAH) in women relative to men and that diminished peripheral chemosensitivity is related to the degree of arterial desaturation during exercise in male endurance athletes. The purpose of this study was to determine the relationship between the acute ventilatory response to hypoxia (AHVR) and EIAH and the potential influence of gender in trained endurance cyclists and untrained individuals. Healthy untrained males (n = 9) and females (n = 9) and trained male (n = 11) and female (n = 10) cyclists performed an isocapnic AHVR test followed by an incremental cycle test to exhaustion. Oxyhemoglobin saturation (Sa(O(2)) was lower in trained men (91.4 +/- 0.9%) and women (91.3 +/- 0.9%) compared to their untrained counterparts (94.4 +/- 0.8% versus 94.3 +/- 0.7%) (P < 0.05). AHVR and maximal O(2) consumption were related for all subjects (r = -0.46), men (r = -0.45) and women (r = -0.53) (P < 0.05) but AHVR was unrelated to Sa(O(2)) for any groups (P > 0.05). We conclude that resting AHVR does not have a significant role in maintaining Sa(O(2)) during sea-level maximal cycle exercise in men or women.

Exercise‐induced arterial hypoxaemia and the mechanics of breathing in healthy young women

•  By virtue of their smaller lung volumes and airway diameters, women develop more mechanical ventilatory constraints during exercise, which may result in increased vulnerability to hypoxaemia during exercise. •  Hypoxaemia developed at all exercise intensities with varying patterns and was more common in aerobically trained subjects; however, some untrained women also developed hypoxaemia. •  Mechanical respiratory constraints directly lead to hypoxaemia in some women and prevent adequate reversal of hypoxaemia in most women. •  Experimentally reversing mechanical constraints with heliox gas partially reversed the hypoxaemia in subjects who developed expiratory flow limitation. •  Due in part to increased mechanical ventilatory constraints, the respiratory systems response to exercise is less than ideal in most women.

Normative data for the modified balance error scoring system in adults.

Primary objective: Head trauma, with or without injury to the brain, can impair balance and postural stability. The Modified Balance Error Scoring System (M-BESS) is a rapid, standardized, objective bedside test that can be helpful for monitoring recovery of balance and postural stability following head trauma. The purpose of this study is to develop preliminary normative data for this test for adults. Methods and procedures: Adults between the ages of 20–69 (n = 1234) were administered the M-BESS as part of a comprehensive preventive health screen. They did not have significant medical, neurological or lower extremity problems that might have an adverse effect on balance. Main outcomes and results: M-BESS performance significantly declined with age. Men and women performed similarly on the M-BESS. There was a small significant difference in M-BESS performance, with obese men performing more poorly than non-obese men and a larger significant difference between obese and non-obese women. Conclusions: The M-BESS normative data are presented for the total sample and by age, sex and age-by-sex. These normative data provide a frame of reference for interpreting M-BESS performance in adults who sustain traumatic brain injuries and adults with diverse neurological problems.