Here is a set of evidence-guided recommendations for warm-up before cross-country skiing, written by Kerry McGawley, Director of the Swedish Winter Sports Centre.
An active warm-up is typically carried out prior to competition in order to increase body temperature, which positively affects a number of important physiological processes. For example, energy (adenosine triphosphate, ATP) is produced more quickly in the muscle at higher temperatures, due to increased rates of phosphocreatine (PCr) utilization and anaerobic glycolysis. In addition, muscle cross-bridge cycling rates are increased when the muscle is warm, allowing faster muscle contraction and relaxation, and warmer muscle fibres appear to have a better "conduction velocity", meaning that peak forces can be developed more quickly. These effects are particularly relevant to sprint racing.
There are other benefits of an active warm-up besides increasing body temperature. For example, performing short exercise bouts at relatively high intensities prior to a race positively affects aerobic metabolism by activating metabolic enzymes, preparing neural pathways and speeding up the oxygen uptake (VO2) response at the start of a race. As a result, aerobic energy is produced more quickly, which is important for both sprint and distance XC skiing performance.
Post-activation potentiation (PAP) is another active warm-up strategy and improves muscular power output over a short duration. PAP refers to the improvement in muscular performance directly after a maximal or near-maximal muscular contraction and appears to be related to neural factors and muscle mechanics. PAP may include resistance exercises or weighted drop/counter-movement (CMJ) jumps performed shortly before competition.
Passive warm-up strategies (e.g., hot water immersion, saunas, electric blankets, heated/survival garments) are typically used to increase or maintain muscle temperature without depleting energy stores. These methods are usually used in the transition period from the end of the active warm-up until the race start. Maintaining an elevated body temperature following an active warm-up is important since a 1°C reduction in muscle temperature may lead to reductions in performance of up to 10%.
Another form of passive warm-up includes psychological preparation, such as visual and preparatory arousal techniques, which allow athletes to focus their attention and build self-confidence. All of these passive warming methods should be used in addition to (not instead of) an active warm-up.
While no published warm-up studies have investigated cross-country skiing, some general practical recommendations can be provided:
• Begin the active warm-up with ~ 15 min of aerobic exercise at 60-70% of maximal heart rate (HRmax), in order to elevate body temperature
• Follow this with a series of higher-intensity efforts, in order to prime VO2 and PAP responses:
Prior to sprint racing (to be finished ~ 7–10 min before the start of the race)
1. A 3-min effort slightly above lactate threshold
2. A 1-min effort slightly harder, between lactate threshold and maximum
3. A 30-s effort slightly harder again, towards maximum
4. Several sets of PAP exercises (e.g., moderate resistance exercises at ~ 60-85% of 1 repetition maximum [RM], weighted drop/counter-movement jumps, or a practical alternative)
Prior to distance racing (to be finished ~ 20 min before the start of the race)
1. A 6-min build effort above lactate threshold towards race-pace intensity
2. Some very short, high-intensity bursts or PAP exercises for an explosive start
During the ~ 7–10 or 20 min transition phases between completing the active warm-up and the start of the race, use a passive heat maintenance strategy (e.g., heated/survival garments)
Also use this time to mentally prepare for the race using visual and/or preparatory arousal techniques
Bailey et al. (2009) "Optimizing the "priming" effect: influence of prior exercise intensity and recovery duration on O2 uptake kinetics and severe-intensity exercise tolerance". J Appl Physiol 107:1743-1756
McGowan et al. (2015) "Warm-Up Strategies for Sport and Exercise: Mechanisms and Applications". Sports Med 45:1523-1546
McGowan et al. (2016) "Current Warm-Up Practices and Contemporary Issues Faced by Elite Swimming Coaches". J Strength Cond Res 30:3471-3480