OBJECTIVE:   To investigate the effect of hand position and lower limb length measurement method on LQ-YBT scores and their interpretation.

DESIGN:   Cross-sectional study.

SETTING:   National Sports Institute of Malaysia.

PATIENTS OR OTHER PARTICIPANTS:   A total of 46 volunteers, consisting of 23 men (age = 25.7 ± 4.6 years, height = 1.70 ± 0.05 m, mass = 69.3 ± 9.2 kg) and 23 women (age = 23.5 ± 2.5 years, height = 1.59 ± 0.07 m, mass = 55.7 ± 10.6 kg).

INTERVENTION(S):   Participants performed the LQ-YBT with hands on hips and hands free to move on both lower limbs.

MAIN OUTCOME MEASURE(S):   In a single-legged stance, participants reached with the contralateral limb in each of the anterior, posteromedial, and posterolateral directions 3 times. Maximal reach distances in each direction were normalized to lower limb length measured from the anterior-superior iliac spine to the lateral and medial malleoli. Composite scores (average of the 3 normalized reach distances) and anterior-reach differences (in raw units) were extracted and used to identify participants at risk for injury (ie, anterior-reach difference ≥4 cm or composite score ≤94%). Data were analyzed using paired t tests, Fisher exact tests, and magnitude-based inferences (effect size [ES], ±90% confidence limits [CLs]).

RESULTS:   Differences between hand positions in normalized anterior-reach distances were trivial (t91 = -2.075, P = .041; ES = 0.12, 90% CL = ±0.10). In contrast, reach distances were greater when the hands moved freely for the normalized posteromedial (t91 = -6.404, P < .001; ES = 0.42, 90% CL = ±0.11), posterolateral (t91 = -6.052, P < .001; ES = 0.58, 90% CL = ±0.16), and composite (t91 = -7.296, P < .001; ES = 0.47, 90% CL = ±0.11) scores. A similar proportion of the cohort was classified as at risk with the hands on the hips (35% [n = 16]) and the hands free to move (43% [n = 20]; P = .52). However, the participants classified as at risk with the hands on the hips were not all categorized as at risk with the hands free to move and vice versa. The lower limb length measurement method exerted trivial effects on LQ-YBT outcomes.

OBJECTIVE: Our aim was to systematically review the scientific literature to identify factors related to the performance of elite sprint cross-country skiers.

METHODS: Four electronic databases were searched using relevant medical subject headings and keywords, as were reference lists, relevant journals, and key authors in the field. Only original research articles addressing physiology, biomechanics, anthropometry, or neuromuscular characteristics and elite sprint cross-country skiers and performance outcomes were included. All articles meeting inclusion criteria were quality assessed. Data were extracted from each article using a standardized form and subsequently summarized.

RESULTS: Thirty-one articles met the criteria for inclusion, were reviewed, and scored an average of 66 ± 7 % (range 56-78 %) upon quality assessment. All articles except for two were quasi-experimental, and only one had a fully-experimental research design. In total, articles comprised 567 subjects (74 % male), with only nine articles explicitly reporting their skiers' sprint International Skiing Federation points (weighted mean 116 ± 78). A similar number of articles addressed skating and classical techniques, with more than half of the investigations involving roller-skiing assessments under laboratory conditions. A range of physiological, biomechanical, anthropometric, and neuromuscular characteristics was reported to relate to sprint skiing performance. Both aerobic and anaerobic capacities are important qualities, with the anaerobic system suggested to contribute more to the performance during the first of repeated heats; and the aerobic system during subsequent heats. A capacity for high speed in all the following instances is important for the performance of sprint cross-country skiers: at the start of the race, at any given point when required (e.g., when being challenged by a competitor), and in the final section of each heat. Although high skiing speed is suggested to rely primarily on high cycle rates, longer cycle lengths are commonly observed in faster skiers. In addition, faster skiers rely on different technical strategies when approaching peak speeds, employ more effective techniques, and use better coordinated movements to optimize generation of propulsive force from the resultant ski and pole forces. Strong uphill technique is critical to race performance since uphill segments are the most influential on race outcomes. A certain strength level is required, although more does not necessarily translate to superior sprint skiing performance, and sufficient strength-endurance capacities are also of importance to minimize the impact and accumulation of fatigue during repeated heats. Lastly, higher lean mass does appear to benefit sprint skiers' performance, with no clear advantage conferred via body height and mass.

LIMITATIONS: Generalization of findings from one study to the next is challenging considering the array of experimental tasks, variables defining performance, fundamental differences between skiing techniques, and evolution of sprint skiing competitions. Although laboratory-based measures can effectively assess on-snow skiing performance, conclusions drawn from roller-skiing investigations might not fully apply to on-snow skiing performance. A low number of subjects were females (only 17 %), warranting further studies to better understand this population. Lastly, more training studies involving high-level elite sprint skiers and investigations pertaining to the ability of skiers to maintain high-sprint speeds at the end of races are recommended to assist in understanding and improving high-level sprint skiing performance, and resilience to fatigue.

OBJECTIVE: To assess the impact of a three-week UDP program onstrength, power, and proprioceptive measures.

DESIGN: Matched-group, pre- post design.

SETTING: National Sports Institute.

PARTICIPANTS: Twenty-one international-level female field hockey athletes.

INTERVENTIONS: Two 45 min UDP sessions were incorporated into each week of a three week training program (total 6 sessions).

MAIN OUTCOME MEASURES: One-repetition maximum strength, lower limb power, 20 m running speed, and proprioception tests were performed before and after the experimental period.

RESULTS: Substantial improvements in running sprint speed at 5- (4.4 ± 2.6%; Effect Size [ES]: 0.88), 10- (2.1 ± 1.9%; ES: 0.51), and 20-m (1.0 ± 1.6%; ES: 0.23) were observed in the UDP group. Squat jump performance was also clearly enhanced when compared to the control group (3.1 ± 6.1%; ES: 0.23). Small but clear improvements in maximal strength were observed in both groups.

METHODS: Athletes (n = 12,526, comprising 13% world class, 21% international, 36% national, 24% state, and 6% recreational) completed an online survey that was available from 17 May to 5 July 2020 and explored their training behaviors (training knowledge, beliefs/attitudes, and practices), including specific questions on their training intensity, frequency, and session duration before and during lockdown (March-June 2020).