Effects of carbohydrate supplementation on competitive runners undergoing overload training followed by a session of intermittent exercise

Abstract

This study evaluated the effects of a micro cycle of overload training (1st-8th day) on metabolic and hormonal responses in male runners with or without carbohydrate supplementation and investigated the cumulative effects of this period on a session of intermittent high-intensity running and maximum-performance-test (9th day). The participants were 24 male runners divided into two groups, receiving 61% of their energy intake as CHO (carbohydrate-group) and 54% in the control-group (CON). The testosterone was higher for the CHO than the CON group after the overload training (694.0 +/- 54.6 vs. CON 610.8 +/- 47.9 pmol/l). On the ninth day participants performed 10 x 800 m at mean 3 km velocity. An all-out 1000 m running was performed before and after the 10 x 800 m. Before, during, and after this protocol, the runners received solution containing CHO or the CON equivalent. The performance on 800 m series did not differ in either group between the first and last series of 800 m, but for the all-out 1000 m test the performance decrement was lower for CHO group (5.3 +/- 1.0 vs. 10.6 +/- 1.3%). The cortisol concentrations were lower in the CHO group in relation to CON group (22.4 +/- 0.9 vs. 27.6 +/- 1.4 pmol/l) and the IGF1/IGFBP3 ratio increased 12.7% in the CHO group. During recovery, blood glucose concentrations remained higher in the CHO group in comparison with the CON group. It was concluded that CHO supplementation possibly attenuated the suppression of the hypothalamic-pituitary-gonadal axis and resulted in less catabolic stress, and thus improved running performance.

Carbohydrate supplementation delays DNA damage in elite runners during intensive microcycle training

“…Likewise, carbohydrate ingestion attenuates the increase of LDH levels and reduces the numbers of circulating leukocytes and monocytes after intermittent running. We have recently shown (de Sousa et al 2010) that carbohydrate ingestion increases testosterone levels after intensive training, enhances running performance, and reduces exercise-induced stress hormone levels as demonstrated by a lower cortisol response after 10 9 800 m running and at 80 min of recovery, in agreement with the present study showing attenuation in the circulating levels of free plasma DNA, LDH, and leukocytes after 10 9 800 m running in the CHO group. According to Febbraio and Pedersen (2002) and McAnulty et al (2007), carbohydrate supplementation during exercise seems to reduce ''exercise stress'' as indicated by lower levels of circulating adrenaline, cortisol, and interleukin-6.…”

“…3), but not with CK (r \ 0.40, p [ 0.05). As reported by de Sousa et al (2010), the cortisol response was attenuated postintermittent running and at 80 min of recovery in the CHO group when compared to the CON group.…”

“…The training program consisted of intense interval and continuous running, mainly in the morning, and moderate continuous running in the afternoon. The complete experimental protocol has been described previously (de Sousa et al 2010). In summary, after the overload training program (day 1-8), the athletes arrived at the running track on day 9 after a 12-h fast and blood samples were collected.…”

“…We have recently shown that long-term carbohydrate supplementation in competitive runners undergoing overload training increased testosterone levels, reduced the post-exercise cortisol response, and improved running performance (de Sousa et al 2010). In the present study, we hypothesize that athletes receiving carbohydrate supplementation have less cellular damage after high-intensity exercise, permitting faster recovery between training sessions.…”

“…A common approach used to gain a competitive advantage is overload training, which is defined as intense training on consecutive days, followed by a less intense training period for recovery. However, this training schedule combined with an inappropriate diet can lead to training failure and may affect the professional career of the athlete at some point (de Sousa et al 2010;Halson and Jeukendrup 2004). The combination of a comprehensive training program with inadequate recovery periods and diet can cause overtraining syndrome and consequently compromise athletic performance (McKenzie 1999).…”