Ski Technique BIATHLON CANADA Biomechanical determinants of - PowerPoint PPT Presentation

Ski Technique BIATHLON CANADA

Biomechanical determinants of cross-country skiing performance: A systematic review. Skiing (speed) performance is strongly linked to: ◦ The speed maintained on certain sections of a race ◦ Maximum speed ◦ Time to exhaustion ◦ The skiing economy Zoppirolli et al. 2020 In general, Canadian biathletes have a ski speed gap to the top nations. Improved ski technique can improve all four of these factors linked to ski (speed) performance. Tactical, fitness, mental, health, equipment also play a role.

Ski technique Goal to promote forward propulsion while minimizing unnecessary movement ◦ Highly effective and powerful propulsion promotes better performance ◦ More even distribution of propulsion between the right and left and/or upper and lower body improves performance ◦ Modern skate technique greatly involves the upper body and body positions to keep the CoM forward ◦ Important to simplify movements and reduce extraneous movement ◦ Increased cycle length can improve propulsion and efficiency

Cycle length and rate Faster skiers have longer cycles length (limited in offset) Higher cycle rate related with maximal speed capacity, while self-selected cycle rate improves skiing economy at sub-maximal speeds Faster skiers generally employ shorter poling and thrust phases in combination with longer gliding and recovery phases

Centre of Mass (CoM) Faster skiers: ◦ Centre of mass (CoM) deviates less from the forward direction of movement while skating ◦ Have lower vertical and lateral displacement of the CoM, and more forward CoM, at pole plant and during the first part of the poling phase . ◦ G reater extension of the hip and knee joints at pole plant ◦ Double push improves cycle length and increases forward body extension. Negatively, it moves CoM more vertically.

Poles Faster skiers: ◦ Begin the poling phase with the poles in a more elevated position with respect to the trunk and angled closer to vertical than did slower skiers (i.e. ahead of their feet). ◦ This puts the ski pole at a less effective angle initially, shoulder and elbow joints were in midrange positions later in the poling phase where pole angle is most effective ◦ Produce greater peak pole force and produce them over a shorter period of time and later in the poling phase ◦ Exhibited more synchronized poling ◦ Enhance poling forces with a higher body position at the time of pole plant that enables the use of gravity, together with active trunk flexion, to elevate pole force

Lower-body Faster skier’s have: ◦ Smaller angles between their skis and the direction of movement ◦ Better RoM of movements of the knee and ankle joints ◦ While skiing uphill with the offset technique faster skiers exhibit symmetric edging and more force generation by the legs .

Timing Recovery phase timing: ◦ Swinging the arms resulted in higher ski forces and increased cycle length, but increases aerobic demands at slow speeds ◦ At moderate-to-high speeds, swinging the arms enhanced the impulse of leg force and self-selected speeds, while reducing anaerobic involvement and improving skiing economy Power phase timing: ◦ Peak poling forces come later as the skier both “falls” onto poles and pushes into the ground ◦ Sequential activation (whip like motion) of muscles is more efficient and creates more power. In one skate, that order is hip, knee, ankle, shoulder, elbow.

Gold Medal Profile (GMP) Update In progress… Key Performance Indicators (KPI) ◦ Ski report card Key Performance Indicators (KPI) ◦ A Power position ◦ Ski technique manual Body pos. B Power line C Ski liftoff A Pole plant B leg kick/Push Timing C Recovery phase

Basic Body Position for Skiing Flexion from ankle (maximize) High Hip (no sitting back) Forward lean with neutral spine/head/pelvis Hips to shoulder (torso) remain stacked (no twisting or dipping) Weight on the ball of the foot, never heel

One Skate: Body position (KPI’s) 1. Power position (KPI) 2. Ski lift off (KPI) Correct 3. Power line (KPI) Incorrect Assessed from the • front view at ski liftoff, and throughout the cycle

One Skate Cycle – KPI’s & Additional Key Points Body position ◦ Cycle start The moment when the foot/ski hits the ground. Experts put their foot down already in a forward body ◦ position (lots of ankle flexion) and prepare an efficient weight transfer. ◦ Ski lift off (KPI) When kicking ski lifts off the ground and everything returning back to high position. Experts are more ◦ relaxed, in a forward position and 100% balanced on top of their ski. ◦ High position When the highest and most forward position in achieved. Experts get a “higher and more forward ◦ position” and spend more time in this position before pole plant. ◦ Power position (KPI) Moment of pushing into the ground. Experts keep forward body position to take advantage of body ◦ weight falling onto poles, apply a “curtsy movement” to push force into the ground. Sequential joint activation is key to maximize power.

4) Power 2) Ski liftoff (KPI) 1) Start 3) High One skate: side body positions

1) Start 4) Power 3) High 2) Ski liftoff (KPI) One skate: front body positions

◦ Power timing When pushing poles into ground ◦ Peak poling power is high and comes later in push ◦ Basic Timing for Leg push is quick (short power impulse) ◦ Sequential activation ◦ Skiing ◦ Recovery timing When returning everything forward after poling ◦ Relaxed return ◦ Sequential activation (body, arms/poles) ◦ Using arms to improve short power impulse in leg push ◦

Offset – Key Points ◦ Body position In offset this position is maintained throughout the cycle and presses forward into the hill ◦ Forward body position at all times (ski liftoff, power phase, etc.) ◦ ◦ Wide feet & ski direction Bring foot straight to where you will kick, not further inside and back out. “V” should be narrow and an even angle on both ◦ ski’s (as pointed forward as possible) ◦ Weight shift 90/90% weight shift (even on each side) ◦ Small rotation to direct energy onto each ski ◦ Quick weight shift, quick impulse off both legs ◦ ◦ Recovery arm swing timing Return the arms to the front in a relaxed way and with the timing to assist a short impulsive kick ◦

Power Ski liftoff Offset: side body position

Correct Incorrect Offset: Power line

Offset: front body position Power line

Athlete needs knowledge on what to look for and develop skills to assess Athletes needs to technique “experience it” • Involve them in assessment • Athlete will take some reps to with video experience it • Build knowledge of proper • Utilize dryland imitations technique • Coach can help explain the “why” How to Teach Ski Technique Athlete needs to “see it” Athlete needs to “feel it” • Quality video from the correct • How does it feel? What are you direction & distance to properly feeling? assess • Often feels a bit strange at first • Vs. a model • Athlete will need to (feel like • Immediate video feedback they) exaggerate movement at much better than delayed (can first to change it offer both) • After athlete shares the • Slow down and/or pause video “feeling”, coach can provide in critical frames to assess direct feedback. accurately

2-3 cold base ski with fine grind 2-3 universal base ski with uni grind Ski Equipment 2 wet base ski with course grind List (Junior) Skate training/rock ski's Ski 1-2 pairs classic race ski 1 pair classic skin ski 2 pairs skate poles 1 pair classic poles