Intermittent Fasting Promotes Weight Loss without Decreasing Performance in Taekwondo

Abstract

Intermittent fasting (IF) is commonly used by combat sports athletes for weight loss. However, IF can decrease performance. This study aimed to investigate the effect of IF on total body mass (TBM) and Taekwondo performance. Nine athletes (seven male, two female; 18.4 ± 3.3 years) underwent 4 weeks of 12 h IF. TBM, countermovement jump (CMJ), mean kicks (MK), and total number of kicks (TNK) were compared weekly. Performance was measured in the fed state (FED) and fast state (FAST). Results showed decreased TBM in week 1 (62.20 ± 6.56 kg; p = 0.001) and week 2 (62.38 ± 6.83 kg; p = 0.022) compared to pre-intervention (63.58 ± 6.57 kg), stabilizing in week 3 (62.42 ± 6.12 kg), and no significant change in week 4 (63.36 ± 6.20 kg). CMJ performance in week 1 was lower in FED (35.26 ± 7.15 cm) than FAST (37.36 ± 6.77 cm; p = 0.003), but in week 3, FED (38.24 ± 6.45 cm) was higher than FAST (35.96 ± 5.05 cm; p = 0.047). No significant differences were found in MK and TNK in FSKTmult. RPE, KDI, and HR were similar between FED and FAST (p < 0.05). [LAC] was higher post-test compared to pre-test (p = 0.001), with higher concentrations in FED than FAST (p = 0.020). BG was higher in FED than FAST (p < 0.05) before physical tests. Therefore, IF promotes decreased TBM without decreasing performance.

Efeitos do jejum intermitente em variáveis fisiológicas e psicobiológicas no Taekwondo durante período pré-competitivo

“…The sample size was determined by convenience. Characterization of the volunteers was performed using dual-energy X-ray absorptiometry (Lunar Prodigy Advance, GE Healthcare, USA) [7].…”

“…Additionally, athletes should not have experienced any type of joint and/or muscle injury in the lower limbs in the previous six months, and should not have used nutritional or pharmacological ergogenic resources within the last 30 days. Furthermore, volunteers answered negatively to all questions in the Physical Activity Readiness Questionnaire [6].…”

“…Fasting, whether acute or chronically intermittent, is a nutritional strategy commonly used in the pre-competition period by Taekwondo athletes, both men and women, to adjust body composition [5][6][7]. Intermittent fasting is carried out over a period of several days or weeks, during which the individual abstains from food intake for predetermined periods, typically between 12 and 24 hours, followed by periods of ad libitum intake, cyclically [8,9].…”

“…These mechanisms may contribute to reduced appetite, lower food and energy intake, both instinctively and voluntarily [12]. Consequently, a negative calorie balance can be established over time, leading to a reduction in total body mass [7,13,14].…”

“…Silva et al [6] found that acute 12-hour fasting before a training session reduced the total body mass of Taekwondo athletes without compromising performance. Silva et al [7] furthered this topic and also obtained results of reduced total body mass without impairing physical, specific, and overall performance when investigating potential effects of 12-hour intermittent fasting over four weeks of Taekwondo training in the pre-competitive period. However, no studies were found that investigated the responses of physiological and psychobiological variables related to the recovery processes and health of Taekwondo athletes undergoing intermittent fasting.…”