The main technical characteristics of sailboard include length, width, and the material of board
The principle of windsurfing is simple; windsurfers stand on the board, with the feet roughly shoulder width apart and hold the rig with the hands for controlling the board. However, competitive windsurfing can be very demanding in physical condition as windsurfers have to execute several maneuvers with a variety of techniques which require a good physical condition.
Until the early 1990s, Olympic class windsurfing was considered as a sport with moderately intense physical activity . Since November 1992, the technique of “sail pumping” maneuver was allowed in all Olympic windsurfing competitions and made the sport much more physically demanding [3–5]. Sail pumping is an action in which board sailors move the rig repeatedly in order to accelerate the board on the waves reaching higher speeds and thus being more competitive. During sail pumping, the peak muscular activity in the arm muscles has been found to be greatest while a considerable activation has been detected in shoulder muscles but much less activity has been recorded for the legs . Particularly, sail pumping requires successive flexion-extension movement of the upper and lower limbs during the whole race, which usually lasts between 25 and 50 min depending on wind conditions . Athletes’ ability for repeatable sail pumping during the race is considered as crucial for the ranking points.
Sail pumping and boardsailing strategies in the race are influenced substantially by weather conditions during the whole duration of the race. Windsurfing in different wind force conditions (light, moderate, and strong) can demonstrate different physiological demands and determinants of performance. It becomes apparent that windsurfers have to follow tailored training programs to meet the physiological demands of races under every weather condition.
27.2 Physiological Responses in Windsurfing
Windsurfing can be extremely demanding in terms of metabolic requirements as it combines surfing and sailing activity . De Vito et al. were the first who demonstrated in actual sailing condition during Olympic boardsailing (Mistral board; sail surface 7.4 m2, board length 3.70 m/width 63 cm) the profound metabolic demands entailing high energy and cardiorespiratory costs [3, 9]. Later, the energy demand of windsurfing was reassessed by Castagna et al.  who found that windsurfing with NeilPryde board (RS:X; sail surface 9.5 m2; board length 2.86 m/width 93 cm), which substituted Mistral, has greater energy demands and requires high levels of aerobic and anaerobic capacity .
The metabolic profile of windsurfing can be described mainly as aerobic; however, the tactical and strategic decisions during a race require also a mixture of explosive-anaerobic force . Specifically, aerobic capacity and fitness condition has been found to be directly related to sailors’ reaction speed to wind shifts  particularly at the last stages of competition. The mean oxygen consumption can be higher than 80 % of VO2max, the average HRmax can be over the 90 %, and the blood lactate concentration can correspond to the values recorded during a maximal treadmill test [3–10]. During the race, windsurfers often exceed their anaerobic thresholds at various intervals while the generated muscle forces can reach an average of 50 % of the maximum voluntary contraction (MVC) [5, 13, 14]. The intensity of the muscle contractions and number of simultaneously activated muscles  has been found much higher than in dingy sailing and during repeatedly tacks maximal activation of the arm muscles is attained .
In windsurfing, the physiological demands appear to be influenced by the strength of the winds. In light to moderate winds, sail pumping has been reported as the main reason for the demands of high levels of physical endurance [5, 16]. Indeed, the metabolic demands of windsurfing increase greatly (by threefold) when sail pumping is performed, as the oxygen consumption (VO2max) can even reach 90 % of maximum oxygen uptake for prolonged periods of time [3, 5]. Furthermore, HR can be greatly increased with a mean HR ranging between 160 and 180 beats/min [5, 17, 18] depending on parameters such as the frequency of sail pumping based on wind force conditions and/or the types of muscle contractions during the windsurfing race . There is a linear relationship between HR and exercise intensity . Subsequent studies including HR measurements [4, 13] during actual windsurfing condition confirmed that sail pumping is a very demanding endurance activity which is closely depended to the heart’s capacity to increase its output. Therefore, cardiac output – the product of heart rate and stroke volume (HR × SV) – has commonly been identified as one limiting factor of endurance performance .
Since the overall demands of aerobic capacity are high in windsurfing under light to moderate winds, lactate levels have been found also increased. Capillary blood lactic acid accumulation reaches an average of 8–9 mmol/l, which is much higher than the lactic acid concentration in dingy sailing . High levels of blood lactate can be also one of the key reasons that limit the athletic effort  during sail pumping activity. In contrast, windsurfing under strong winds, which requires isometric contraction of the upper limb body muscles, is characterized by lower lactic acid accumulation which reaches on average the 3.0–5.0 mmol/l . Even the relative low lactate levels (i.e., 3.0–5.0 mmol/l) sustained in isometric contraction of the upper limb muscles can be considered of sufficient intensity to induce muscle fatigue during contractions above 20–30 % of maximum voluntary contraction (MVC) due to ischemia . Therefore, ischemia can be considered as an additional limiting factor of performance in windsurfing under strong wind conditions.
27.2.1 The Determinants of Windsurfing Performance
A good physical condition and muscular strength are generally considered as important characteristics for increased performance in Olympic boardsailing. The lower back, shoulder, and arm muscles have been identified for their high activation in windsurfing . Upper body strength and endurance are critical for windsurfers to maintain control of board and achieve a good performance in regattas. However, in contrast to most other sports, wind force conditions have a crucial role in boardsailing performance as the wind velocity determines the frequency of sail pumping during boardsailing and provide a different pattern of physical effort based on the wind force conditions.
Sail pumping maneuver is considered substantially effective when the wind velocity is up to 15 knots (7 m/s) and requires a good aerobic capacity. In stronger winds, however, sail pumping loses its efficacy or it becomes so physically demanding . This is due to the fact that pumping action is needed to increase the speed of the surfboard when the wind is not strong enough, but in high velocity winds, the technique is not effective. In strong winds, the nature of boardsailing physical effort is mostly isometric as the pumping technique is being replaced by a constant near isometric pulling power that is needed to control the board against the strong winds. Therefore, it is reasonable that the determinants of the performance in windsurfing are highly influenced by the wind velocity and the strategy followed during the race in which the frequency of sail pumping and the nature of physical effort (aerobic or isometric) differ.
27.2.2 Studies for the Effect of Light and Moderate Wind Force Conditions
In light to moderate winds, board sailors need to pump the sail repeatedly providing the board with additional speed. The first study that investigated the energy demands of sail pumping compared to non-pumping conditions was published in 2002 by the group of Vogiatzis et al. . Physiological responses such as oxygen consumption (VO2), minute ventilation (VE), and heart rate (HR) during the sail pumping were significantly increased compared to sailing without pumping in both men and women (Fig. 27.2) . Moreover, all these parameters with an exemption of HR were significantly higher in men compared to women; however, these differences did not remain in non-pumping conditions between the sexes (Fig. 27.2) . These observations have not substantially changed since 2006 when a new board (NeilPryde RS:X; 9.5 m2men and 8.5 m2 women) equipped with a larger sail was established for Olympic events.
Data of Vogiatzis et al.  demonstrated different physiological responses in oxygen uptake (VO2), ventilation (VE), and heart rate (HR) during boardsailing with sail pumping or without sail pumping in men and women. Data are means ±SD. Asterisks denote significant differences between with and without sail pumping condition. (a) Men, (b) women
Boardsailing in light to moderate wind conditions can be considered as a high-level aerobic activity when sail pumping maneuvers are frequently performed. The level of aerobic capacity has been measured to range between 70 and 92 % of VO2max similar to most of aerobic sports such as cycling, running, swimming, etc. [5, 16]. Moreover, the average HR during race in light wind conditions has been found to reach 170 beats/min, while average lactate concentration is approximately 8.5 mmol/l [19, 26]. Previously, differences in the HR increase during competitive boardsailing in two wind force conditions (light vs. moderate) have been reported regarding to sail pumping . Guevel et al.  demonstrated that HR was higher in light compared to moderate wind force conditions (87 ± 4 % vs. 83 ± 5 % HRmax) while blood lactate concentration did not differ between wind conditions . In general, light and medium wind Olympic windsurfing performance is highly dependent on the capacity of the athlete to maintain a high cardiac output for long periods of time with a maximal oxygen uptake of over 75 % [7, 19]. Moreover, high blood lactate accumulation can also impact negatively the performance of windsurfers in races with light to moderate wind force conditions as large amounts of lactic acid in the muscles can accelerate fatigue. It is reasonable that cardiac output can be identified as a key factor for the performance of windsurfers under light and medium wind force conditions. Cardiac output can become the main limiting factor in windsurfing under light to moderate wind conditions, as it can explains 70–85 % of the variance in VO2max [21, 27].