- Top of page
Greater gender differences have been found in exercise modes where the upper body is involved. Therefore, the present study investigated the influence of poling on gender differences in endurance performance by elite cross-country skiers. Initially, the performance of eight male and eight female sprint skiers was compared during four different types of exercise involving different degrees of poling: double poling (DP), G3 skating, and diagonal stride (DIA) techniques during treadmill roller skiing, and treadmill running (RUN). Thereafter, DP was examined for physiological and kinematic parameters. The relative gender differences associated with the DP, G3, DIA and RUN performances were approximately 20%, 17%, 14%, and 12%, respectively. Thus, the type of exercise exerted an overall effect on the relative gender differences (P < 0.05). In connection with DP, the men achieved 63%, 16%, and 8% higher VO2peak than the women in absolute terms and with normalization for total and fat-free body mass (all P < 0.05). The DP VO2peak in percentage of VO2max in RUN was higher in men (P < 0.05). The gender difference in DP peak cycle length was 23% (P < 0.05). In conclusion, the present investigation demonstrates that the gender difference in performance by elite sprint skiers is enhanced when the contribution from poling increases.
During the last decade, research has revealed that the performance of elite male athletes in connection with endurance sports is approximately 10–12% better than that of elite female athletes with similar condition (Joyner, 1993; Schumacher et al., 2001; Coast et al., 2004; Maldonado-Martin et al., 2004; Seiler et al., 2007). Most of the gender difference associated with endurance sports has been attributed to a higher VO2max and lower percentage of body fat in men (Joyner, 1993; Calbet & Joyner, 2010). However, in the case of elite sprint cross-country skiing uphill on roller skis using the skating G3 technique, the gender difference was recently found to be approximately 17% (Sandbakk et al., 2012). Because poling generates much of the propulsion in G3 skating (Millet et al., 1998; Stöggl et al., 2011), this more pronounced gender difference in comparison with other sports may reflect more effective poling in male skiers. Studies on other sports reveal greater work rates in swimming than in running and speed skating (Seiler et al., 2007), which may further support the hypothesis of greater gender differences when the upper body is involved.
In cross-country skiing, the manner in which the arms and legs are employed changes with the terrain and the technique utilized (Smith, 1992). Specifically, with the double poling technique (DP), propulsion is powered exclusively by the poling itself (e.g., Nilsson et al., 2004; Holmberg et al., 2005). Therefore, if the more pronounced gender difference associated with G3 skating is due to poling, this difference should be even greater with DP than with techniques that rely less on poling.
Accordingly, the current investigation was designed to compare gender differences in endurance performance among elite skiers utilizing three different techniques that rely on poling to different extents (from extensively to not at all), i.e., DP, G3 skating and diagonal stride roller skiing, as well as running on a treadmill. Thereafter, the findings on DP were examined in greater detail with respect to physiological and kinematic characteristics. Our hypothesis was that the difference between the performance of the men and women is positively correlated to the contribution of poling, and that the gender differences in performance and kinematics connected with DP cannot be explained by differences in peak oxygen uptake (VO2peak) and percentage body fat alone.
- Top of page
The current investigation was designed to compare gender differences in endurance performance among elite skiers utilizing three different techniques that rely on poling to different extents. The size of gender differences on performance (i.e., peak speed) was associated with the amount of poling contribution. The gender differences ranged from 20% in DP (mostly poling) to 12% in RUN (model for no poling), with 17% and 14% in G3 and DIA. In absolute work rates, these gender differences were 67%, 62%, 58%, and 54% for DP, G3, DIA, and RUN. In DP, we examined the gender differences in more detail. The differences in VO2peak normalized for total (16%) and fat-free (8%) body mass were somewhat smaller than differences in work rates. The work rate differences in DP were mostly due to a longer cycle length with no significant gender difference in cycle rate.
Our comparison of performance associated with DP, G3, DIA, and RUN, ranging from exclusively poling in DP to no poling in RUN, clearly revealed an effect of poling intensity on gender differences. The 20% gender difference in peak speed associated with DP decreased to 17% with G3, 14% with DIA and 12% with RUN. The approximately 10–12% gender differences in performance reported for comparable sports, are not different with those observed with RUN here (Schumacher et al., 2001; Coast et al., 2004; Maldonado-Martin et al., 2004; Seiler et al., 2007). Thus, the 20% gender difference associated with DP was significantly greater.
Work rate is related to an exponential expression of velocity, and the magnitudes of difference in work rate associated with a given performance are, in many cases, more correct representations of the actual gender differences (Seiler et al., 2007). In the current study, gender differences in work rates across exercise modes revealed the same results as the comparisons of peak speed. An additional finding was that the gender differences for RUN almost disappeared (3%) when work rate was normalized for fat-free body mass, whereas these differences increased with the poling contribution. Overall, the calculations of work rate further support our hypothesis that the performance difference between men and women is positively correlated to the contribution of poling.
The current study reported greater gender differences in all roller ski modes than the ∼10% difference between genders in mean speeds during FIS sprint races from 2000 to 2008 (Stöggl et al., 2008). However, the world cup races performed over similar distances from 2010 to 2012 show that gender differences between the top 10 skiers have increased from 12% to 16%. This indicates increasing gender differences among sprint skiers in recent years, probably reflecting a greater degree of specialization for sprint skiing in male skiers. Despite this, performance in the tests employed here does not necessarily reflect the actual difference between genders in sprint skiing competitions; we believe our protocols are highly relevant for examining the gender differences between exercise modes. Furthermore, the validity of the tests are supported by the significant correlations between FIS points and peak speed in all roller ski tests employed, and that performance in a similar test was strongly correlated to sprint time-trial performance in the skating technique (Sandbakk et al., 2011c).
It was also of interest to compare our findings with sports where most of the propulsion is generated by the upper body. With various distances, the gender differences in the mean speeds of world record holders at the end of 2010 were approximately 11% for swimming and rowing, and approximately 13% for kayaking. However, the quadratic influence of velocity on opposing frictional forces and the fact that the boats are deeper in the water with heavier men leads to larger differences in work rate than the time differences indicate in these sports. Seiler et al. (2007) report larger differences in the work rates produced when swimming (approximately 45%) where the upper body is highly involved, compared with running and speed skating (20–30%), where only the legs produce propulsion. Altogether, these data support our findings of a more effective utilization of the upper body in men.
Our more in-depth analysis of DP revealed that in this case the gender differences were associated with higher VO2peak both in absolute values and relative to VO2max in the male sprint skiers. With respect to VO2peak, this gender difference was consistently greater than those observed for comparable endurance sports (Joyner, 1993; Calbet & Joyner, 2010) and might explain, at least in part, the more pronounced gender difference. Previous investigations have attributed differences in performance between men and women to higher levels of hemoglobin and less body fat in the men (Joyner, 1993; Stefani, 2006; Calbet & Joyner, 2010). Overall, this confirms the hypothesis that the gender differences connected with DP cannot be explained by differences in peak oxygen uptake (VO2peak) and the percentage of body fat alone.
In the present examination of DP performance, male skiers executed a longer cycle length (i.e., work per cycle) both at submaximal and peak speeds, whereas the cycle rate differed only at submaximal speed. This demonstrates that cycle length is the key differentiating factor with respect to DP performance by men and women, in agreement with a previous study by Lindinger and colleagues (2009), showing that for male skiers performing the DP technique, increased speed is associated with longer cycle length. In comparison with what we have reported for the same subjects with the G3 skating technique on a similar incline (see Sandbakk et al., 2012), with DP here the gender difference in cycle length were slightly greater.