Abstract
tivation performance enhancement (PAPE) is a physiological phenomenon that refers to an acute excitation of the neuromuscular system following intense exercise that ends in enhanced physical performance in a subsequent bout of exercise. The scientific literature has primarily examined the effectiveness of PAPE alone or combined with caffeine (CAF) intake in all-out tests lasting≤10 s, as the effect of PAPE is transitory. The aim of the present study was to determine the effect of a protocol to induce PAPE alone or in combination with caffeine intake on the 30 s Wingate Anaerobic Test in highly trained boxers. Twenty-five male
the effectiveness of PAPE alone or combined with caffeine (CAF) intake in all-out tests lasting≤10 s, as the effect of PAPE is transitory. The aim of the present study was to determine the effect of a protocol to induce PAPE alone or in combination with caffeine intake on the 30 s Wingate Anaerobic Test in highly trained boxers. Twenty-five male and highly trained boxers (mean age: 20±1 years) participated in a double-blind, randomized crossover study consisting of three different experimental conditions: (i) control (CON), with no substance intake and no PAPE protocol before the Wingate Anaerobic Test; (ii) PAPE + PLA, involving the intake of a placebo 60 min before and a PAPE protocol comprising a 10 s cycling sprint overloaded with 8.5% of the participants’ body weight 10 min before the Wingate Anaerobic Test; and (iii) PAPE + CAF, involving the intake of 3 mg/kg of caffeine 60 min before and the same PAPE protocol used in the (ii) protocol before the Wingate Anaerobic Test. In all conditions, the participants performed the 30 s version of the Wingate Anaerobic Test with a load equivalent to 7.5% of their body weight, while the cycle ergometer setting was replicated. Immediately following the Wingate test, heart rate (HR), the rating of perceived exertion (RPE), and blood lactate concentration (Bla) were measured. In comparison to CON, PAPE + PLA enhanced mean power (p= 0.024; Effect size [ES] = 0.37) and total work (p= 0.022; ES = 0.38) during the Wingate test, accompanied by an increase in post-test blood lactate concentration (p< 0.01; ES = 0.83). In comparison to CON, PAPE + CAF enhanced mean power (p= 0.001; ES = 0.57), peak power (p= 0.013; ES = 0.57), total work (p= 0.001; ES = 0.53), post-test blood lactate concentration (p< 0.001; ES = 1.43) and participants’ subjective perception of power (p= 0.041). There were no differences in any variable between PAPE + PLA and PAPE + CAF. In summary, a PAPE protocol that involves a 10 s all-out sprint 10 min before the Wingate Anaerobic Test was effective in enhancing Wingate mean power in
0.53), post-test blood lactate concentration (p< 0.001; ES = 1.43) and participants’ subjective perception of power (p= 0.041). There were no differences in any variable between PAPE + PLA and PAPE + CAF. In summary, a PAPE protocol that involves a 10 s all-out sprint 10 min before the Wingate Anaerobic Test was effective in enhancing Wingate mean power in highly trained boxers. The addition of 3 mg/kg of caffeine to the PAPE protocol produced an effect on mean power of a higher magnitude than PAPE alone, and it enhanced peak power along with participants’ subjective perception of power. From a practical point of view, PAPE before exercise seems to be an effective approach for increasing Wingate performance in highly trained boxers, while the addition of caffeine can increase some benefits, especially peak power. Keywords:performance enhancement drug; ergogenic aid; combat sport; stimulation; athlete Nutrients2024,16, 235.
Nutrients2024,16, 235 2 of 14 1. Introduction In recent years, sports practitioners have been looking for new methods to acutely improve athletes’ performance, for example, via the use of physical [1–5] and nutritional [6–10] strategies carried out moments before the onset of exercise. One of the more researched topics within the physical strategies performed before exercise to increase physical performance is the use of short and intense exercise protocols to produce a post-activation potentiation enhancement (PAPE) [11–14]. PAPE, in essence, is a physiological phenomenon that produces an acute excitation of the neuromuscular system following an intense exercise bout. With the appropriate time of recovery, the neuromuscular excitation may produce enhanced physical performance in a subsequent bout of exercise [15]. A large number of studies have confirmed the existence of PAPE, but they suggest that the exercise protocol to induce PAPE has to be of maximal (or near) intensity, while PAPE is primarily effective in enhancing short and high-intensity activities [ Evidence also suggests that one of the key factors in optimizing PAPE is that the exer- cise performed to induce neuromuscular excitation should mimic the movement patterns of the subsequent exercise bout [19,20]. For example, a recent investigation that used a 10 s all-out sprint against a load equivalent to 8.5% of participants’ body weight for the induction of PAPE showed a significant increase of 0.6% in peak power and 2.2% in mean power during the 30 s Wingate Anaerobic Test performed 10 min after the PAPE proto- col [20]. However, the time of recovery between the PAPE protocol and the exercise bout is also crucial. For example, a cycling-based PAPE protocol lasting 20 min with exercise of progressive intensity and 2×20 s sprints tended to be more effective in enhancing cycling performance during a 4 min maximal-performance test when there was 20 min instead of 6 min of recovery [21]. Interestingly, the time of recovery between the PAPE protocol and the exercise bout may be dependent on the PAPE protocol, as it may be as short as 3 min if the PAPE protocol includes jumps and sprints with and
enhancing cycling performance during a 4 min maximal-performance test when there was 20 min instead of 6 min of recovery [21]. Interestingly, the time of recovery between the PAPE protocol and the exercise bout may be dependent on the PAPE protocol, as it may be as short as 3 min if the PAPE protocol includes jumps and sprints with and without sled towing [22]. From a practical point of view, the efficacy of PAPE may rely on a net balance between fatigue and potentiation [23], suggesting that the exercise performed to induce PAPE has to be intense enough to produce neuromuscular excitation but there has to be enough time for recovery before the bout of exercise to avoid fatigue dampening the potential excitatory enhancement. While PAPE on its own provides an attractive solution for coaches to acutely improve exercise performance, other methods may be synergistically applied to PAPE protocols, such as nutritional interventions. Among all the possible nutritional strategies to be combined with PAPE, caffeine seems the most promising as it may potentiate the excitatory effects of PAPE [22]. The effect of the acute intake of caffeine is one of the most frequently researched topics in the field of sports nutrition, as there is extensive research suggesting that caffeine enhances all-out exercise performance [24–26]. For example, a meta-analysis including 16 studies on the effect of caffeine on performance during the Wingate Anaerobic Test showed that caffeine significantly increased peak and average power [27]. Although there is plenty of evidence to support that both PAPE and caffeine intake enhance all-out exercise performance when used alone, studies about the synergy of combining PAPE protocols and caffeine intake are scarce and contradictory [22,28,29]. The addition of 5 mg/kg of caffeine to a PAPE protocol augmented the PAPE effect on jump performance in football players [22]. Likewise, the addition of 3 mg/kg of caffeine to a PAPE protocol augmented the PAPE effects on several taekwondo-specific exercise tests that include agility movements and kicking [28]. However, the addition of 6 mg/kg of caffeine to a PAPE protocol had no additional effect over PAPE on the
protocol augmented the PAPE effect on jump performance in football players [22]. Likewise, the addition of 3 mg/kg of caffeine to a PAPE protocol augmented the PAPE effects on several taekwondo-specific exercise tests that include agility movements and kicking [28]. However, the addition of 6 mg/kg of caffeine to a PAPE protocol had no additional effect over PAPE on the jumping performance of volleyball players [29]. Beyond the scarcity of data, the aforementioned studies tested the combination of PAPE and caffeine in exercise tests of≤10 s (i.e., jumping, agility tests, and 10 s kicking tests). However, there seems to be a gap in current research focusing on tests lasting more than 10 s. Given the variations in energy supply systems across different performance durations [30], it becomes evident that the assessment of exercise performance in a task lasting longer than 10 s is essential to expand understanding of the effects of PAPE alone or in combination with
Nutrients2024,16, 235 3 of 14 caffeine during short-term all-out exercise. Moreover, the 30 s Wingate test stands out as the “gold standard” to assess anaerobic capability as it correlates with performance in various sports events [31–35], encompassing disciplines such as running, cycling, skating, swimming, jumping, and combat sports. The widely recognized validity of the 30 s Wingate test makes it the best method for evaluating anaerobic capacity as its measurement involves the assessment of the adenosine triphosphate and phosphocreatine system (ATP-PCr; as peak power) and the glycolytic system (as mean power) [36]. Of all the athletes that may benefit from the effect of PAPE alone or in combination with caffeine, boxers are among the ones with a higher potential benefit as boxing is a sport characterized by short and explosive movements. Overall, a boxing match is characterized by intermittent bursts of high-intensity activity, interspersed with periods of low-intensity or paused activity due to holds by boxers or referee interruptions [37,38]. The action-to- rest ratio is approximately 3:1 [39]. This pattern of activity demands a substantial level of anaerobic capacity [40] to effectively meet the energy demands of the box matching. Moreover, it has been observed that while boxing is primarily aerobic in nature, crucial movements such as offensive scoring or knockout (KO) maneuvers rely predominantly on anaerobic metabolism [41]. In addition, several articles have been published showing that interventions in the lower body can improve upper body performance [14,42,43]. This suggests that improvements in lower body power, as measured by the Wingate test, might have the potential to translate into enhanced punching power for boxers. This might be the reason why many studies have measured Wingate performance among boxers [44–46]. For all the expressed above, the aim of the present study was to determine the effect of a protocol to induce PAPE alone or in combination with caffeine intake on the 30 s Wingate Anaerobic Test in highly trained boxers. We used boxers to fulfill this aim, as combat sports entail all-out movements and maneuvers with contributions from both aerobic [47] and anaerobic metabolism [48]. We hypothesized that the addition
study was to determine the effect of a protocol to induce PAPE alone or in combination with caffeine intake on the 30 s Wingate Anaerobic Test in highly trained boxers. We used boxers to fulfill this aim, as combat sports entail all-out movements and maneuvers with contributions from both aerobic [47] and anaerobic metabolism [48]. We hypothesized that the addition of caffeine to a PAPE protocol would induce an augmentation of the PAPE effect on Wingate performance. 2. Methods 2.1. Participants A total of 30 male boxers from Beijing Sport University were recruited for this study. All participants recruited for the study were provincial- to national-level athletes, possess- ing a minimum of 4 years (5±1 years) of boxing training experience. These individuals have achieved notable success, having won at least one provincial competition or secured a position within the top-5 ranking in a national competition. To control for individual differences in habitual responsiveness to caffeine due to tolerance, only participants with a daily caffeine intake of less than 50 mg/d were included [49]. We used only male boxers because the potential impacts of PAPE [50] may be influenced by gender-specific factors. This choice aimed to mitigate potential confounding variables associated with gender, ensuring a more focused examination of the targeted effects. In addition to daily caffeine intake, inclusion criteria were as follows: (i) absence of neuromuscular and musculoskeletal disorders, (ii) resistance training experience of at least 2 years, and (iii) self-described satisfactory health status. If participants reported (i) a positive smoking status or (ii) a potential allergy to caffeine, they were excluded from the experiment. Twenty-five male athletes met these inclusion/exclusion criteria (age: 20±1 years; height: 178±4 cm; body weight: 80±12 kg) and completed all experiments. An efficacy analysis conducted using G*POWER 3.1.9.6 (University of Kiel, Germany) indicated that 24 participants were required for this study. The analysis assumed an efficacy of 0.80, an alpha level of 0.05, an effect size of 0.27, and a correlation of 0.5 between repeated measures. The chosen effect size was derived from previous meta-analyses comparing caffeine versus placebo on the Wingate test [27]. Each
using G*POWER 3.1.9.6 (University of Kiel, Germany) indicated that 24 participants were required for this study. The analysis assumed an efficacy of 0.80, an alpha level of 0.05, an effect size of 0.27, and a correlation of 0.5 between repeated measures. The chosen effect size was derived from previous meta-analyses comparing caffeine versus placebo on the Wingate test [27]. Each participant was familiar with sprint-based cycling exercises, and participants were allowed to withdraw from the experiment at any time. All participants were informed about the objectives and potential risks of the study before providing written informed consent for participation. The study protocol was approved by the Sports Science
Nutrients2024,16, 235 4 of 14 Experiments of Beijing Sport University (No. 2023161H) and was conducted in accordance with the ethical standards of the Declaration of Helsinki. 2.2. Study Design Participants attended one familiarization session and three randomized experimental sessions over a ~3-week period, with each experimental session separated by one week (refer to Figure). The familiarization session was implemented at the beginning of the experiment and was primarily designed to obtain body characteristic assessments and to acquaint participants with the experimental procedure and the tests to be conducted, aiming to prevent any potential learning effect. Comfortable seat height and handlebar position on the cycle ergometer were set and recorded for later experimental sessions. At least 48 h after the familiarization session, the experimental sessions were conducted in a randomized order. The order of the trials for each participant was assigned using the randomization feature provided by the online software51].Nutrients 2024, 16, x FOR PEER REVIEW 4 of 14 weight: 80 ± 12 kg) and completed all experiments. An efficacy analysis conducted using G*POWER 3.1.9.6 (University of Kiel, Germany) indicated that 24 participants were re- quired for this study. The analysis assumed an efficacy of 0.80, an alpha level of 0.05, an effect size of 0.27, and a correlation of 0.5 between repeated measures. The chosen effect size was derived from previous meta-analyses comparing caffeine versus placebo on the Wingate test [27]. Each participant was familiar with sprint-based cycling exercises, and participants were allowed to withdraw from the experiment at any time. All participants were informed about the objectives and potential risks of the study before providing writ- ten informed consent for participation. The study protocol was approved by the Sports Science Experiments of Beijing Sport University (No. 2023161H) and was conducted in accordance with the ethical standards of the Declaration of Helsinki. 2.2. Study Design Participants attended one familiarization session and three randomized experimental sessions over a ~3-week period, with each experimental session separated by one week (refer to Figure 1). The familiarization session was implemented at the beginning of the experiment and was primarily designed to obtain body characteristic
conducted in accordance with the ethical standards of the Declaration of Helsinki. 2.2. Study Design Participants attended one familiarization session and three randomized experimental sessions over a ~3-week period, with each experimental session separated by one week (refer to Figure 1). The familiarization session was implemented at the beginning of the experiment and was primarily designed to obtain body characteristic assessments and to acquaint participants with the experimental procedure and the tests to be conducted, aim- ing to prevent any potential learning effect. Comfortable seat height and handlebar posi- tion on the cycle ergometer were set and recorded for later experimental sessions. At least 48 h after the familiarization session, the experimental sessions were conducted in a ran- domized order. The order of the trials for each participant was assigned using the ran- domization feature provided by the online software RANDOM.ORG [51]. The three conditions under experimentation were as follows: (i) control (CON), which involved no substance intake and no PAPE protocol before the Wingate Anaerobic Test; (ii) PAPE + PLA, which involved a placebo intake 60 min before and a PAPE protocol comprising a 10 s cycling sprint overloaded with 8.5% of the participants’ body weight 10 min before the Wingate test; and (iii) PAPE + CAF, the intake of 3 mg/kg of caffeine 60 min before and the same PAPE protocol used in the (ii) protocol 10 min before the Wingate test. (Figure 1). In all conditions, the participants performed a 5 min warm-up and then performed the 30 s version of the Wingate Anaerobic Test with a load equivalent to 7.5% of their body weight while the cycle ergometer setting was replicated. Immediately fol- lowing the Wingate test, heart rate (HR) and the rating of perceived exertion (RPE) were measured, whereas blood samples were obtained 1 min after the Wingate test to assess blood lactate concentration (Bla). All trials were performed in a laboratory with controlled ambient temperature and humidity (24 ± 1 °C and 43 ± 2%, respectively). The primary outcomes for this study were power parameters derived from the Wingate test. Secondary outcomes involved pertinent
(RPE) were measured, whereas blood samples were obtained 1 min after the Wingate test to assess blood lactate concentration (Bla). All trials were performed in a laboratory with controlled ambient temperature and humidity (24 ± 1 °C and 43 ± 2%, respectively). The primary outcomes for this study were power parameters derived from the Wingate test. Secondary outcomes involved pertinent physiological parameters such as HR, RPE, and Bla and other parameters such as subjective perceived fitness and prevalence of side effects. Figure 1. Experimental design. CON = control; PAPE = post-activation performance enhancement protocol; PLA = placebo; CAF = caffeine; HR = heart rate; RPE = rating of perceived exertion; Bla = blood lactate concentration. Figure 1.Experimental design. CON = control; PAPE = post-activation performance enhancement protocol; PLA = placebo; CAF = caffeine; HR = heart rate; RPE = rating of perceived exertion; Bla = blood lactate concentration. The three conditions under experimentation were as follows: (i) control (CON), which involved no substance intake and no PAPE protocol before the Wingate Anaerobic Test; (ii) PAPE + PLA, which involved a placebo intake 60 min before and a PAPE protocol comprising a 10 s cycling sprint overloaded with 8.5% of the participants’ body weight 10 min before the Wingate test; and (iii) PAPE + CAF, the intake of 3 mg/kg of caffeine 60 min before and the same PAPE protocol used in the (ii) protocol 10 min before the Wingate test. (Figure). In all conditions, the participants performed a 5 min warm-up and then performed the 30 s version of the Wingate Anaerobic Test with a load equivalent to 7.5% of their body weight while the cycle ergometer setting was replicated. Immediately following the Wingate test, heart rate (HR) and the rating of perceived exertion (RPE) were measured, whereas blood samples were obtained 1 min after the Wingate test to assess blood lactate concentration (Bla). All trials were performed in a laboratory with controlled ambient temperature and humidity (24±1 ◦ C and 43±2%, respectively). The primary outcomes for this study were power parameters derived from the Wingate test. Secondary outcomes involved
Description
This research investigates the impact of PAPE and caffeine on anaerobic performance in boxers.