Aerobic fitness and yo-yo continuous and intermittent tests performances in soccer players: a correlation study

Yo-yo tests are very popular in soccer; however, no study has addressed details of their relation to canonical aspects of aerobic fitness. Furthermore, no information is available on the effect of the individual levels of lower limbs' explosive strength on yo-yo tests in soccer players. The purpose of this study was to examine the physiological determinants of Yo-yo Endurance Test Level 2 (YYETL2) and Yo-yo Intermittent Recovery Test Level 1 (YYIRTL1) in soccer players. Twenty-four soccer players (body mass, 74.6 +/- 8.5 kg; height, 178.1 +/- 4.5 cm; age, 25.6 +/- 5.1 years) were tested for VO2max and ventilatory threshold (VT) on a motorized treadmill. Lower-limb explosive strength was assessed using vertical countermovement jumps (CMJ) performed on a force platform. Results showed that YYETL2 and YYIRTL1 performances (m) were significantly related (r = 0.75, p = 0.00002). YYETL2 results were significantly related to VO2max, VTVO2, and speed at VT (r = 0.75, 0.76, and 0.83, respectively; p < 0.00002). Peak treadmill speed results were significantly related to YYETL2 and YYIRTL1 (r = 0.87 and 0.71, respectively; p < 0.0003). YYIRTL1 was related to CMJ peak power (r = 0.57; p = 0.003). These findings show that YYETL2 and YYIRTL1, although adopting similar starting and progression speeds, are influenced by different physiological variables. From these results, YYETL2 can be considered an aerobic fitness-related field test, whereas YYIRTL1 can be regarded as an aerobic-anaerobic, soccer-specific field test.     

Relationship between push phase and final race time in skeleton performance

The aim of this study was to examine the relationship between push-time and final race time in skeleton participants during a series of major international competitions to determine the importance of the push phase in skeleton performance. Correlations were computed from the first and second heat split data measured during 24 men and 24 women skeleton competitions. Body mass, height, age, and years of experience of the first 30 men and women athletes of the skeleton, bobsleigh and luge 2003-2004 World Cup ranking were used for the comparison between sliding sports. Moderate but significant correlations (p < 0.05) were found between push-time and final race time in men (r(mean) = 0.48) and women (r(mean) = 0.63). No correlations were found between changes in the individual push-time between the first and second heat with the corresponding changes in final race time. The bobsleigh sliders are heavier than the athletes of the other sliding disciplines. Luge athletes have more experience and are younger than bobsleigh and skeleton sliders. The results of this study suggest that a fast push phase is a prerequisite to success in competition and confirms that the selection of skeleton athletes based on the ability to accelerate to a maximum speed quickly could be valid. However, a good or improved push-time does not ensure a placement in the top finishing positions. On the basis of these results, we suggest that strength and power training is necessary to maintain a short push-time but additional physical training aimed to enhance the push phase might not reflect performance improvements. The recruitment of younger athletes and an increase of youthful competitive activity may be another effective way to reach international competitive results.     

Is it time to consider a new performance classification for high-level male marathon runners?

La Torre, A, Vernillo, G, Agnello, L, Berardelli, C, and Rampinini, E. Is it time to consider a new performance classification for high-level male marathon runners? J Strength Cond Res 25(12): 3242-3247, 2011-Studies have attempted to describe human running performances by the analysis of world-record times. However, to date, no study has analyzed the evolution of high-level marathon performances over time. Thus, the purpose of this study was to analyze these performances across the past 42 years with the aim of delineating a time-based classification. To identify the nature of the phenomenon represented by the sequence of observations, we examined the data collected (i.e., 8,400 times from 1969 to 2010) as a time series. The leading time (LT) and the mean 200 times (T200) per year underwent a nonlinear but significant decrement (r = -0.92, p < 0.001 and r = -0.98, p < 0.001, respectively). In fact, from 1969 to 2010, the mean time differences were 3 minutes 20 seconds ± 1 minute 59 seconds and 7 minutes 1 second ± 2 minutes 48 seconds, corresponding to an improvement of 5 and 10 seconds per year for LT and T200, respectively. Furthermore, trend analysis suggested a disruption in marathon time improvements, indicating the presence of 3 points in the time series in which the performance significantly improved with respect to that of the previous years, corresponding to the years 1983-1984 (p < 0.001), 1997-1998 (p < 0.003), and 2003 (p < 0.001). In conclusion, despite the trend in high-level marathon performances being better explained by a nonlinear tendency, significant improvements in the ability of the high-level marathon runners to complete the distance were observed. These improvements are likely to be related to sociological, environmental, physiological, and training-method factors. Researchers and coaches should take into account these enhancements by using the time classification proposed in this study to better reflect the marathon performance profile of their athletes.     

Effects of gradient and speed on freely chosen cadence: The key role of crank inertial load

The purpose of this study was to describe the relationship between road gradient (RG) and freely chosen cadence (FCC) in a group of professional cyclists during their normal training. In addition, a calculation of crank inertial load (CIL) was estimated in order to establish the relationship between FCC and CIL. Ten professional cyclists were monitored during training using commercially available power meters (Shoberer Rad Messtechnik (SRM), professional version). For each cyclist, recorded training sessions were reviewed to identify the hardest 6–8 training sessions (～18 h of training). RG was estimated based on the relationship between power output, total mass and speed. The analysis was performed using 2113±317 samples of 30 s average data, collected on terrain ranging from ?4%_RG to 12%_RG. The individual relationship between FCC and RG could be described by a linear regression model. There was a moderate correlation between FCC and CIL (group's r=0.42), and a multiple regression including the measured power output (W_PO) increased the variance explained (R²=0.24). The correlation was very large between CIL and v (r=0.91), and was not strengthened by adding W_PO as an independent variable (r=0.91). In conclusion, this investigation documents that in professional cyclists engaged in training, there is a linear decrease in FCC as RG increases (?4%_RG and 12%_RG). This decrease in FCC appears to be due to the reduction in v as slope increases. It is surmised that CIL plays a key role in the modulation of FCC.     

Differences in cortisol, aldosterone and testosterone responses to ACTH 1-17 administered at two different times of day

The effects of 100 micrograms, i.m. of the analog ACTH 1-17 administered at 0800 and 1800 on the secretion of cortisol, aldosterone and testosterone have been studied in normal subjects: 8 male and 8 female. The group as a whole and the males had significantly greater absolute and percent increments in plasma cortisol after administration at 1800. In the females, there was only a greater percent increment in cortisol after the evening administration. The heptadecapeptide always significantly stimulated serum aldosterone, with no difference between the two times of administration. In the females, ACTH 1-17 significantly stimulated testosterone, with a more protracted secretion after the evening administration. In the males, there was always a significant testosterone decrease after the administration of the drug, with no difference between morning and evening. In conclusion, 100 micrograms i.m. of the analog ACTH 1-17 stimulates cortisol secretion more when given during the circadian nadir of plasma cortisol, but only in men. ACTH 1-17 increases testosterone in women and decreases it in men, whereas it seems to increase aldosterone secretion in both sexes.