Impact of environmental factors on knee injuries in male and female recreational skiers

Impact of Environmental Factors on the ACL Injury Risk in Recreational Alpine Skiing

In recreational alpine skiing, an ACL injury represents the most common injury. Skiing is a complex activity where the skier interacts with the environment, such as weather, snow conditions, temperature, etc. Thus, the aim of this study was to evaluate the potential impact of environmental factors on ACL injury risk in recreational alpine skiers. Among a cohort of 392 ACL-injured skiers and 392 uninjured controls matched for sex and skiing skill, environmental factors were collected by questionnaire. Factors included weather conditions, snow conditions, perceived temperature, and slope difficulty at the time-point of the accident (ACL-injured skiers) or of questioning during the ski day (uninjured controls).Multiple logistic regression revealed that in addition to age, five environmental factors were significantly predictive of an ACL injury: fresh snow (OR 10.5), grippy snow (OR 7.8), icy slope condition (OR 12.4), very cold/cold perceived temperature (OR 1.6), and skiing on easy slopes (OR 6.9). In conclusion, besides age, environmental factors such as fresh and grippy snow, icy slope conditions, low temperatures, and flat slopes are associated with an increased ACL injury risk in recreational alpine skiing. Those factors are at least partly modifiable and should be taken into consideration for preventive strategies.

Muscular Fatigue and Quadriceps-to-Hamstring Ratio in Alpine Skiing in Women over 40 Years

(1) Background: In alpine skiing, senior athletes and especially women have a high risk of knee injury. This may also be related to muscular fatigue (MF) of the knee-stabilizing thigh muscles. This study investigates both the evolution of muscle activity (MA) and of MF of the thighs throughout an entire skiing day. (2) Methods: n = 38 female recreational skiers over 40 years of age performed four specific skiing tasks (plough turns, V-steps uphill, turns with short, and middle radii) at specific times, while freely skiing the rest of the day. Surface EMG of the thigh muscle groups (quadriceps and hamstrings) was measured using special wearables (EMG pants). Apart from standard muscle activity parameters, the EMG data were also processed in the frequency domain to calculate the mean frequency and its shift over the day as a metric of muscle fatigue. (3) Results: The EMG pants showed reliable signal quality over the entire day, with BMI not impacting this. MF increased during skiing before and for both muscle groups significantly (p < 0.006) during lunch. MF, however, was not reflected in the quadriceps-hamstrings ratio. The plough manoeuvre seems to require significantly (p < 0.003) more muscle dynamics than the three other tasks. (4) Conclusion: MF may be quantified over an entire skiing day and thus fatigue information could be given to the skier. This is of major importance for skiers at the beginner level dominantly performing plough turns. Crucial for all skiers: There is no regenerative effect of a 45-min lunch break.

Effect of Weather and Game Factors on Injury Rates in Professional Baseball Players

BACKGROUND

Injury rates in baseball players of all ages are increasing. Identifying modifiable risk factors is paramount to implementing injury prevention programs.

PURPOSE/HYPOTHESIS

The purpose was to evaluate the influence of weather (temperature, humidity, atmospheric pressure, and heat index) and game factors (start time, duration, single vs doubleheader) on injury rates in professional baseball players. We hypothesized that colder temperatures would be associated with significantly more injuries per game.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

This was a retrospective database study. Two data sets were combined: 1 containing all injuries in Major and Minor League Baseball between 2011 and 2017 and 1 containing all games played in Major and Minor League Baseball during the same period to determine the number of injuries per game. Temperature, humidity, atmospheric pressure, and heat index were determined for each game using the data from the US Environmental Protection Agency. Additional game variables included the level of play, the turf type (natural vs artificial grass), the stadium type (open vs dome vs retractable), the game start time, the game duration, and whether the game was a doubleheader. Then, a multivariate analysis was conducted to determine which factors were associated with the number of injuries per game.

RESULTS

In total, our analysis included 33,587 injuries and 76,747 games. A total of 25,776 (33.6%) games contained an injury, and 41% of injuries occurred as multiples per game, with up to 9 injuries per game. The multivariate analysis identified significant associations between game duration and injuries per game (P < .001; effect size, 0.013) and the level of play and injuries per game (P < .001; effect size, 0.011). There were significant associations between the venue type (P < .001), the game start time (P < .001), humidity (P < .001), the turf type (P = .016), and barometric pressure (P = .031); however, the effect size for each was <0.001, suggesting that these factors are clinically unimportant. Our overall model produced an R² of 0.04, indicating that these variables only predicted 4% of the variance in injury risk.

CONCLUSION

In professional baseball, the weather is not associated with injury risk; however, game duration may contribute to injury risk.

Practicing Sport in Cold Environments: Practical Recommendations to Improve Sport Performance and Reduce Negative Health Outcomes

Although not a barrier to perform sport, cold weather environments (low ambient temperature, high wind speeds, and increased precipitation, i.e., rain/water/snow) may influence sport performance. Despite the obvious requirement for practical recommendations and guidelines to better facilitate training and competition in such cold environments, the current scientific evidence-base is lacking. Nonetheless, this review summarizes the current available knowledge specifically related to the physiological impact of cold exposure, in an attempt to provide practitioners and coaches alike with practical recommendations to minimize any potential negative performance effects, mitigate health issues, and best optimize athlete preparation across various sporting disciplines. Herein, the review is split into sections which explore some of the key physiological effects of cold exposure on performance (i.e., endurance exercise capacity and explosive athletic power), potential health issues (short-term and long-term), and what is currently known with regard to best preparation or mitigation strategies considered to negate the potential negative effects of cold on performance. Specific focus is given to "winter" sports that are usually completed in cold environments and practical recommendations for physical preparation.

A Prospective Injury Surveillance Study on Ski Touring

Background:

Ski touring is an outdoor sport with growing popularity in alpine countries. Information about injuries in ski touring is limited.

Purpose:

To determine injury rates, mechanisms, causes, and risk factors in ski touring.

Study Design:

Descriptive epidemiology study.

Methods:

Between November 2015 and May 2016, a total of 191 participants from the Alps region were prospectively tracked via personalized online questionnaires. Injury rates were calculated per 1000 hours of sports exposure. Risk factors were assessed per multivariate logistic regression analysis.

Results:

A total of 3900 ski tours were performed, with 10,955 hours and 4,108,503 m in height ascension (uphill) recorded. The overall injury rate was 2.5 injuries per 1000 hours of ski touring. A total of 27 injury-events were reported, of which 18 (67%) were classified as mild, 7 (26%) as moderate, and 2 (7%) as severe. Hands (28%) and knees (16%) were the most commonly involved anatomic regions. Most injuries were limited to the soft tissue, such as bruises (31%) and abrasions (18%). Significantly more injuries happened during the descent (n = 17; 63%) than during the ascent (n = 6; 22%) (odds ratio, 5.96; P = .004), while poor weather conditions, icy surface, and inattentiveness were the most often reported reasons for injury. Sidecountry ski touring was identified as the only significant independent risk factor for injury (P < .001).

Conclusion:

In this prospective injury surveillance study, the majority of ski touring injuries were mild and limited to the soft tissue. Ski touring injuries were more likely to happen during the descent of a tour, and sidecountry ski touring was the only significant independent risk factor for injury. Bad weather, icy surface, and inattentiveness were found to be the leading causes for an injury-event in this study.

Effects of Visual and Auditory Perturbations on Ski-Specific Balance among Males and Females-A Randomized Crossover Trial

Injuries in skiing show sex-specific differences, especially when visual perception is reduced. Reduced visual perception impairs balance, which plays an important role in avoiding skiing injuries. However, males and females might cope differently with reduced visual perception. Thus, the aim of this study was to evaluate sex-related effects of environmental perturbations (reduced visual perception and listening to music) on ski-specific balance. Using a crossover design, ski-specific balance was tested in 50 young adults (50% female) in four conditions: with and without listening to music and/or with and without reduced visual perception (ski goggles with occlusion foil). A four × two (condition by sex) mixed ANOVA revealed a significant condition by sex interaction, partial η² = 0.06. Females showed an increase in balance from the condition without music/with normal visual perception to the condition with music/with normal visual perception, while males showed a decrease. Balance was significantly higher in females compared to males, partial η² = 0.31. The findings suggest that balance is affected differently by environmental perturbations in females and males. However, the differences observed were not in line with our initial hypotheses, which might be because the model was too simplistic for how visual/auditory perturbations may affect balance.

Effect of environmental conditions on injury rates at a Colorado ski resort

OBJECTIVE

To determine the effect of daily environmental conditions on skiing and snowboarding-related injury rates.

METHODS

Injury information was collected from a mountainside clinic at a large Colorado ski resort for the 2012/2013 through 2016/2017 seasons. Daily environmental conditions including snowfall, snow base depth, temperature, open terrain and participant visits were obtained from historical resort records. Snowpack and visibility information were obtained for the 2013/2014 through 2014/2015 seasons and included in a subanalysis. Negative binomial regression was used to estimate injury rate ratios (IRRs) and 95% CIs.

RESULTS

The overall injury rate among skiers and snowboarders was 1.37 per 1000 participant visits during 2012/2013 through 2016/2017. After adjustment for other environmental covariates, injury rates were 22% higher (IRR=1.22, 95% CI 1.14 to 1.29) on days with <2.5 compared with ≥2.5 cm of snowfall, and 14% higher on days with average temperature in the highest quartile (≥-3.1°C) compared with the lowest (<-10.6°C; IRR=1.14, 95% CI 1.03 to 1.26). Rates decreased by 8% for every 25 cm increase in snow base depth (IRR=0.92, 95% CI 0.88 to 0.95). In a subanalysis of the 2013/2014 and 2014/2015 seasons including the same covariates plus snowpack and visibility, only snowpack remained significantly associated with injury rates. Rates were 71% higher on hardpack compared with powder days (IRR=1.71, 95% CI 1.18 to 2.49) and 36% higher on packed powder compared with powder days (IRR 1.36, 95% CI 1.12 to 1.64).

CONCLUSIONS

Environmental conditions, particularly snowfall and snowpack, have a significant impact on injury rates. Injury prevention efforts should consider environmental factors to decrease injury rates in skiers and snowboarders.

Influence of Extrinsic Risk Factors on National Football League Injury Rates

Background:

The risk of injury associated with American football is significant, with recent reports indicating that football has one of the highest rates of all-cause injury, including concussion, of all major sports. There are limited studies examining risk factors for injuries in the National Football League (NFL).

Purpose:

To identify risk factors for NFL concussions and musculoskeletal injuries.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

Injury report data were collected prospectively for each week over the 2012-2013 and 2013-2014 regular seasons for all 32 teams. Poisson regression models were used to identify the relationship between predetermined variables and the risk of the 5 most frequent injuries (knee, ankle, hamstring, shoulder, and concussion).

Results:

A total of 480 games or 960 team games (TGs) from the 2012-2013 and 2013-2014 regular seasons were included in this study. A trend to an increasing risk of concussion and TG ankle injury with decreasing mean game-day temperature was observed. The risk of TG concussion (incidence rate ratio [IRR], 2.16; 95% CI, 1.35-3.45; P = .001) and TG ankle injury (IRR, 1.48; 95% CI, 1.10-1.98; P = .01) was significantly greater for TGs played at a mean game-day temperature of ≤9.7°C (≤49.5°F) compared with a mean game-day temperature of ≥21.0°C (≥69.8°F). The risk of TG shoulder injury was significantly increased for TGs played on grass surfaces (IRR, 1.36; 95% CI, 1.02-1.81; P = .038) compared with synthetic surfaces. The risk of TG injury was not associated with time in season, altitude, time zone change prior to game, or distance traveled to a game.

Conclusion:

This study evaluated extrinsic risk factors for injury in the NFL. A hazardous association was identified for risk of concussion and ankle injury with colder game-day temperature. Further research should be conducted to substantiate this relationship and its potential implication for injury prevention initiatives.

Changes in Skiing and Snowboarding Injury Epidemiology and Attitudes to Safety in Big Sky, Montana, USA: A Comparison of 2 Cross-sectional Studies in 1996 and 2013

Background

Despite a risk of harm, the past 20 years have seen dramatically increased participation in snow sports such as skiing, and particularly, snowboarding. This period has also seen revolutions in piste maintenance and paradigm developments in the use of safety equipment. Consequently, the numbers and characteristics of injury may be very different from those traditionally quoted.

Purpose

To compare and evaluate the injury patterns among skiers and snowboarders in a North American ski resort in 1996 and 2013.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Questionnaire-based cross-sectional studies were carried out independently in a North American ski resort between the dates of March 6 and April 11 in both 1996 and 2013. Demographic data and information about incident circumstances were collected from injured patients who visited the local on-site clinic. Data were compared statistically to assess for significant changes in injury characteristics between the 2 time periods.

Results

The 1996 report consisted of 148 injured participants, and the 2013 study included 156 participants. Results from 2013 demonstrated significant increases in helmet use, the number of snowboarders injured, and shoulder injuries. Injury was also more likely in those aged 46 to 55 years, those never having had professional instruction, or those with rented equipment. Significant reductions were seen in those injured with other people close by and in the 36- to 45-year age group. Overall, the knee was the most commonly injured body part in both periods (1996: 31%, n = 38; 2013: 33%, n = 36), although upper limb injuries were predominant in snowboarders.

Conclusion

Snow sports injury characteristics of patients presenting to a ski resort medical clinic have changed between 1996 and 2013. These findings can be used to further inform safety recommendations and areas to target with further research.

Decrease in eccentric quadriceps and hamstring strength in recreational alpine skiers after prolonged skiing

Background

To effectively prevent injury in recreational alpine skiing, it is important to identify modifiable risk factors that can be targeted through exercise and training. Fatigue is a potential risk factor in recreational skiing, but no investigations have evaluated concentric/eccentric quadriceps and hamstring fatigue in recreational skiers. We tested the hypothesis that recreational skiing is associated with more pronounced eccentric as compared with concentric muscle fatigue.

Methods

Twenty-four healthy and fit recreational skiers (14 male and 10 female) performed an isokinetic muscle test 1 day before, 1 h after, and 24 h after a 4 h skiing session. The testing protocol consisted of concentric and eccentric quadriceps and hamstring contractions for both legs.

Results

Eccentric peak hamstring torque (both thighs) and eccentric peak quadriceps torque (left thigh) were reduced in male and female participants (p<0.05). Reduced peak torques were still present 24 h after the skiing session. There were no other significant findings.

Summary

Recreational skiing is associated with prolonged (at least 24 h) eccentric quadriceps (left thigh) and hamstring (both thighs) fatigue in men and women. Eccentric quadriceps and hamstring fatigue may be a potential injury risk factor in male and female recreational skiers. This provides some justification for judicious use of additional eccentric training modalities for alpine skiing.

Microclimate in ski boots--temperature, relative humidity, and water absorption

Ski boot quality is determined by mechanical properties and comfort. Comfort is strongly affected by cold feet. The purpose of this study was to determine the microclimate in ski boots. Climate chamber tests with five male subjects and field tests with two male subjects were conducted. Temperature and relative humidity were measured using four sensors placed on the foot and one on the liner. Absorbed water in liners and socks was measured with a precision balance. The subjects gave subjective ratings for comfort. The toe sensor temperature dropped below 20 °C at an ambient temperature of 0 °C, -10 °C, and -20 °C. Relative humidity values at the foot were as high as 78% in the climate chamber and 93% in the field. Water absorption in socks and liners ranged from 4 to 10 g in the climate chamber and 19 to 45.5 g in the field. The results reveal the importance of keeping the feet and in particular the toes warm during skiing. One possible improvement may be to construct the liner so that sweat and melted snow are kept as far away as possible from the foot. Liner material with high water absorption capacity and hydrophobic socks were suggested to prevent wet feet.

Knee Injuries in Downhill Skiers: A 6-Year Survey Study

BACKGROUND

Knee injuries account for approximately one third of injuries in skiers. Researchers have proposed several mechanisms of knee injury in skiers. However, the frequencies of these mechanisms have varied in different studies.

PURPOSE

To identify the most common knee injury mechanisms in recreational downhill skiers and to assess injury frequencies across several demographics.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

Over 6 ski seasons, 541 patients with acute knee injuries completed a survey. Patients selected 1 of 6 injury classifications; age, sex, height, weight, years of experience, ability level, and ski binding release were also recorded.

RESULTS

The overall injury distribution was valgus-external rotation (32.9%), phantom foot (22.5%), hyperextension (19.0%), boot induced (7.8%), collision (2.2%), and other (15.6%). The phantom foot mechanism was most common in ages 30 to 40 years (36.3% of all injuries within this mechanism; P < .01). Children and adults showed no significant difference in distribution of injury mechanism. Of 80 youth skiers, valgus-external rotation was most common (35.4%), followed by phantom foot (25.3%). Adult and youth skiers who identified as "advanced" skiers had a higher prevalence of valgus-external rotation than did less experienced skiers (51.5% of total valgus injuries; P < .01). Bindings released in 19.3% in adults and 53.7% in youths (P < .01) during injury. Female skiers comprised 60.0% of total respondents, but only 39.7% of injuries occurred in female children (P < .01).

CONCLUSION

Valgus-external rotation is the most common injury mechanism for recreational skiers in general. Previous studies have suggested that the phantom foot injury is the most common injury, but in this series, it was the second most common, representing 22.5% of injuries in this study. Individuals between the ages of 30 and 40 years showed an increased risk for the phantom foot mechanism, and the prevalence of injuries was significantly higher for females compared with males in this cohort (P < .01). Children and adults appear to have similar mechanisms for ski-related knee injuries, with valgus-external rotation being most common and advanced skiers having the highest frequency of this mechanism. Binding release was more likely to occur in youth skiers.

The +1245g/t polymorphisms in the collagen type I alpha 1 (col1a1) gene in polish skiers with anterior cruciate ligament injury

Objectives

The aim of this study was to examine the association of +1245G/T polymorphisms in the COL1A1 gene with ACL ruptures in Polish male recreational skiers in a case-control study.

Methods

A total of 138 male recreational skiers with surgically diagnosed primary ACL ruptures, all of whom qualified for ligament reconstruction, were recruited for this study. The control group comprised 183 apparently healthy male skiers with a comparable level of exposure to ACL injury, none of whom had any self-reported history of ligament or tendon injury. DNA samples extracted from the oral epithelial cells were genotyped for the +1245G/T polymorphisms using real-time PCR method.

Results

Genotype distributions among cases and controls conformed to Hardy-Weinberg equilibrium (p = 0.2469 and p = 0.33, respectively). There was a significant difference in the genotype distribution between skiers and controls (p = 0.045, Fisher's exact test). There was no statistical difference in allele distribution: OR 1.43 (0.91-2.25), p = 0.101 (two-sided Fisher's exact test).

Conclusions

The risk of ACL ruptures was around 1.43 times lower in carriers of a minor allele G as compared to carriers of the allele T.

Factors associated with injuries occurred on slope intersections and in snow parks compared to on-slope injuries

In alpine winter sports, external risk factors as snow and weather conditions as well as slope characteristics (width, steepness, slope intersections, and snow parks) should be considered when investigating potential risk factors. Therefore, ski patrol injury reports were used to compare factors associated with injuries occurred on slope intersections and in snow parks compared to on-slope injuries. Multivariate regression analysis revealed that in comparison to injuries occurring on ski slopes, collisions with other persons (OR: 2.1, 95% CI: 1.3-3.4) and arm injuries (OR: 2.1, 95% CI: 1.3-3.5) were more likely associated with injuries occurring on slope intersections while male gender (OR: 3.5, 95% CI: 2.1-5.7), younger age (OR: 1.1, 95% CI: 1.0-1.1), slushy/soft snow conditions (OR: 1.9, 95% CI: 1.1-3.3), knee injuries (OR: 0.4, 95% CI: 0.2-0.8) and back injuries (OR: 5.5, 95% CI: 3.0-10.2) were more likely associated with injuries which occurred in snow parks. In conclusion, injuries on slope intersections and in snow parks differ in some factors from injuries sustained on ski slopes.