Downhill skiing is considered to be an enjoyable activity for children and adolescents, but it is not without its risks and injuries. Injury rates now range between 3.9 and 9.1 injuries per 1000 skier days, and there has been a well documented increase in the number of trauma cases and fatalities associated with this sport. Head and neck injuries are considered the primary cause of fatal injuries and constitute 11-20% of total injuries among children and adolescents. Cranial trauma is responsible for up to 54% of total hospital injuries and 67% of all fatalities, whereas thoracoabdominal and spine injuries comprise 4-10% of fatalities. Furthermore, there has been an increase in the proportion of upper extremity trauma with acromioclavicular dislocations, and clavicle and humeral fractures accounting for the majority (22-79%) of the injuries. However, the most common and potentially serious injuries in children and adolescents are those to the lower extremity, with knee sprains and anterior cruciate ligament tears accounting for up to 47.7% of total injuries. Knee sprains and grade III ligament trauma associated with lower leg fractures account for 39-77% of ski injuries in this young population. Approximately 15% of downhill skiing injuries among children and adolescents are caused by musculoskeletal immaturity. Other factors include excessive fatigue, age, level of experience, and inappropriate or improperly adjusted equipment. Collisions and falls constitute a significant portion (up to 76%) of trauma, and are commonly associated with excessive speed, adverse slope conditions, overconfidence leading to carelessness, and behavioural patterns within and among gender. The type and severity of injuries are typically functions of biomechanical efficiency, skiing velocity or slope conditions; however, a multiplicative array of intrinsic and extrinsic factors may simultaneously be involved. Despite extensive efforts to provide a comprehensive picture of the aetiology of injury, limitations have hampered reporting. These limitations include age and injury awareness, data collection challenges, lack of uniformity in the definition or delineation of age classification and lack of knowledge of predisposing factors prior to injury. Since skill level is the primary impetus in minimising ski injuries, formal instruction focusing on strategies such as collision avoidance and helmet use, fall training minimising lower extremity trauma, altering ski technique and avoiding behaviours that lead to excessive risk are, therefore, highly recommended. Skiing equipment should be outfitted to match the young skier's height, weight, level of experience, boot size and slope conditions. Additionally, particular attention should be paid to slope management (i.e. overcrowding, trail and obstacle marker upkeep) and minimising any opportunity for excessive speed where children are present. Whether increases in knowledge, education and technology will reduce predisposition to injury among this population remains to be seen. As with all high-ri...

This study examined sex-specific responses during self-paced, high-intensity interval training (HIIT). Sixteen (8 men and 8 women) individuals completed a peak oxygen uptake test and 3 treadmill HIIT sessions on separate days. The HIIT sessions consisted of six 4-minute intervals performed at the highest self-selected intensity individuals felt they could maintain. Recovery between intervals was counterbalanced and consisted of 1-, 2-, or 4-minute recovery during each trial. Relative measures of intensity, including percentage of velocity at VO2peak (vVO2peak), %VO2peak, %HRmax, and blood lactate concentration ([La]), were observed during the trials. Perceived readiness was recorded immediately before and ratings of perceived exertion (RPE) were recorded at the end of each interval with session RPE recorded after each trial. Results revealed a significant effect of sex on %vVO2peak (p < 0.01) and %HRmax (p < 0.01). Data show that across trials, men self-select higher %vVO2peak (84.5 vs. 80.7%), whereas women produce higher %HRmax (96.9 vs. 92.1%) and %VO2peak (89.6 vs. 86.1%) with no difference in [La] or perceptual responses. These findings support the notion that women may demonstrate improved recovery during high-intensity exercise, as they will self-select intensities resulting in greater cardiovascular strain. Moreover, results confirm previous findings suggesting that a 2:1 work-to-rest ratio is optimal during HIIT for both men and women.

The 30-s Wingate anaerobic test (30-WAT) is the most widely accepted protocol for measuring anaerobic response, despite documented physical side effects. Abbreviation of the 30-WAT without loss of data could enhance subject compliance while maintaining test applicability. The intent of this study was to quantify the validity of the 20-s Wingate anaerobic test (20-WAT) versus the traditional 30-WAT. Fifty males (mean +/- SEM; age = 20.5 +/- 0.3 years; Ht = 1.6 +/- 0.01 m; Wt = 75.5 +/- 2.6 kg) were randomly selected to either a validation (N = 35) or cross-validation group (N = 15) and completed a 20-WAT and 30-WAT in double blind, random order on separate days to determine peak power (PP; W kg(-1)), mean power (MP; W kg(-1)), and fatigue index (FI; %). Utilizing power outputs (relative to body mass) recorded during each second of both protocols, a non-linear regression equation (Y (20WAT+10 )= 31.4697 e(-0.5)[ln(X (second)/1174.3961)/2.6369(2)]; r (2) = 0.97; SEE = 0.56 W kg(-1)) successfully predicted (error approximately 10%) the final 10 s of power outputs in the cross-validation population. There were no significant differences between MP and FI between the 20-WAT that included the predicted 10 s of power outputs (20-WAT+10) and the 30-WAT. When derived data were subjected to Bland-Altman analyses, the majority of plots (93%) fell within the limits of agreement (+/-2SD). Therefore, when compared to the 30-WAT, the 20-WAT may be considered a valid alternative when used with the predictive non-linear regression equation to derive the final power output values.

The PPG method is a promising technique with an inherent potential for automatisation of the ankle pressure measurements, thereby reducing the observer-dependency in ABPI recordings.

Morgan, AL, Laurent, CM, and Fullenkamp, AM. Comparison of V[Combining Dot Above]O2peak performance on a motorized vs. a nonmotorized treadmill. J Strength Cond Res 30(7): 1898-1905, 2016-Despite growing popularity of nonmotorized treadmills (NMTs), little data exist regarding responses during exercise testing using this equipment, which is important when providing an appropriate exercise prescription. The purpose of this study was to evaluate physiological and perceptual responses during peak graded exercise tests (GXTs) on a motorized treadmill (MT) vs. NMT. Volunteers (12 men and 12 women aged 18-35 years) performed 2 peak GXT sessions (1 MT and 1 NMT). Respiratory gases and heart rate (HR) were collected each minute; perceptual response was estimated (Borg's 6-20 rating of perceived exertion [RPE] scale) during the final 10 seconds of each stage. Peak values (i.e., V[Combining Dot Above]O2, HR, speed) were determined during the final 10 seconds of each test; ventilatory threshold (VT) was assessed using the V-slope method. Paired t-tests matching variables measured at each stage of the GXT identified significantly higher values on the NMT for V[Combining Dot Above]O2 83% of the time, HR 67% of the time, and RPE 25% of the time. Interestingly though, neither peak V[Combining Dot Above]O2 (48.6 ± 9.2 ml·kg·min vs. 47.8 ± 8.9 ml·kg·min), peak HR (185 ± 9 b·min vs. 188 ± 10 b·min; p = 0.90), nor VT (72.7 ± 5.7% vs. 73.8 ± 5.4%) were significantly different on the NMT vs. the MT. However, significant differences were identified between NMT and MT tests for time to exhaustion (9:55 ± 1:49 vs. 12:05 ± 2:48; p < 0.01) and peak speed (8.0 ± 0.9 mph vs. 9.2 ± 1.4 mph; p < 0.01). Thus, although peak values obtained were similar between testing sessions on the NMT and MT, the majority of submaximal data were significantly different between trials. These differences are important when designing exercise prescriptions using submaximal values from NMT testing that may be inappropriately high or low at corresponding intensities during training.