Abstract
Objectives: A high level of specific metabolic capacity is essential for maximal sprinting in both male and female athletes. Various factors dictate sex differences in maximal power production and energy utilization. This study aims to compare the contribution of energy systems between male and female athletes with similar sport-specific physiological adaptations during a 15-s sprint exercise.Methods: The endurance group consisted of 17 males (23±7 y) and 17 females (20±2 y). The speed-power group included 14 males (21.1±2.6 y) and 14 females (20±3 y). The contribution of phosphagen, glycolytic, and aerobic systems was determined using the three-component PCr-LA-O 2method.Results: Significant differences were observed in the energy expenditure for all systems and total energy expenditure between males and females in both groups (p= 0.001–0.013). The energy expenditure in kJ for individual systems (phosphagen– glycolytic–aerobic) was 35:25:7 vs. 20:16:5 in endurance males vs. female athletes, respectively. In the speed-power group, male athletes expended 33:37:6 kJ and female athletes expended 21:25:4 kJ, respectively. The percentage proportions did not differ between males and females in any system. The contribution of the phosphagen–glycolytic–aerobic systems was 52:37:11 vs. 48:39:13 in endurance male and female athletes, respectively. For speed-power males vs. female athletes, the proportions were 42:50:8 vs.
female athletes, respectively. In the speed-power group, male athletes expended 33:37:6 kJ and female athletes expended 21:25:4 kJ, respectively. The percentage proportions did not differ between males and females in any system. The contribution of the phosphagen–glycolytic–aerobic systems was 52:37:11 vs. 48:39:13 in endurance male and female athletes, respectively. For speed-power males vs. female athletes, the proportions were 42:50:8 vs. 41:50:9, respectively.Conclusions:Despite the differences in body composition, mechanical output, and absolute energy expenditure, the energy system contribution appears to have a similar metabolic effect between male and female athletes engaged in sprint exercises with similar sport-related adaptations. The magnitude and profile of sex differences are related to sports discipline. Keywords:glycolytic; phosphagen; aerobic; sprint; energy expenditure; sex differences 1. Introduction The relatively limited intramuscular ATP (adenosine triphosphate) stores(~5 mmol per kg of wet muscle) result in insufficient sustainability of contractile activity for extended peri- ods. If stored ATP were the sole energy source during all-out exercise, the activity could be sustained for less than 2 s [1]. To restore ATP, activation of other metabolic pathways is necessary, which can be achieved through three integrated energy systems [2]. During exercise, ATP resynthesis is contributed to by all pathways in both anaerobic and aerobic processes. However, the extent of their involvement varies depending on the type, intensity, and duration of the sports activity. The phosphagen system (anaerobic) relies on the degradation of phosphocreatine to creatine and the subsequent rephosphorylation of adenosine diphosphate to ATP. Together with cellular ATP reserves, this system dominates and delivers immediate energy during the initial moments of sprinting. The main reactions within the phosphagen system are creatine kinase, adenylate kinase, and adenosine monophosphate deaminase. The glycolytic system (anaerobic) operates by replenishing ATP sourced from blood glucose and muscle glycogen. Its activity increases during exercises lasting longer than a few seconds, J. Clin. Med.2024,13, 4812.
J. Clin. Med.2024,13, 4812 2 of 15 utilizing a non-mitochondrial pathway [3]. Glycolysis involves a sequence of reactions that can be segmented into two phases: (i) an initial “investment” phase, necessitating the consumption of two ATP molecules, and (ii) a subsequent “payoff” phase where a net generation of ATP molecules takes place [4]. The aerobic system facilitates ATP resynthesis through mitochondrial respiration in the presence of oxygen. Within this system, free fatty acids and glycogen serve as the primary fuel sources for replenishing energy via the oxidation of carbohydrates, lipids, and amino acids [2,5]. Since different exercises elicit distinct metabolic demands, each sport and exercise modality exhibits a specific utilization pattern of these energy systems [6–9]. Sprinting is essential in competitive sports, contributing significantly to both speed-power and endurance disciplines due to factors such as acceleration, overtaking, and finishing [2]. Thus, there is a necessity for high performance in maximal sprint exercise across various sports. A number of factors directly or indirectly influence the contribution of energy systems during maximal sprint exercise and determine sex differences in producing maximal power. These are primarily physique and body composition [10], physiological [11], biochemi- cal [12,13], and biomechanical [14] factors. Although many studies have been conducted on sex differences, few have directly compared the contribution of energy systems between the sexes during sprinting. In one study, the authors analyzed martial artists using the Wingate test [15]. Other researchers compared men and women in the 100 and 200 m sprints [7]. On one hand, it was indicated that no sex differences were reported in the percentage contribution of energy systems; on the other hand, significant differences were reported in the total energy cost (kJ) between the sexes. Contrastingly, one study showed significant differences both in absolute and relative values in the comparison of males and females in repeated sprint tests [16]. The reports are not conclusive, and it is essential to note that the same sports adaptation and the lack of use of body descriptors, such as skeletal muscle mass (SMM) or leg lean mass (LLM), might potentially impact the outcome and further interpretations.
in absolute and relative values in the comparison of males and females in repeated sprint tests [16]. The reports are not conclusive, and it is essential to note that the same sports adaptation and the lack of use of body descriptors, such as skeletal muscle mass (SMM) or leg lean mass (LLM), might potentially impact the outcome and further interpretations. To our best knowledge, no one directly considered sex differences in energy system contribution during sprinting in the context of the specificity of the disciplines. Such data may help determine whether the quality of training stimuli should be diversified by sex. In addition, coaches and sports scientists may be provided with insights into the specific athletic predispositions of male and female athletes and help them select appropriate sports disciplines or specialties. Therefore, the present study aimed to compare the contribution of energy systems to sprinting exercise between male and female athletes practicing the same type of sport: speed and power or endurance. We hypothesize that there are sex differences in the contribution of the energy systems during sprints and that they are affected by sports specialization. 2. Materials and Methods 2.1. Participants Initially, this study incorporated a cohort of 102 athletes representing diverse disci- plines who underwent examinations during the general preparation period. After obtaining the data, male and female athletes were carefully selected to meet the criterion of a similar value of the peak and mean power per kilogram of skeletal muscle mass within each athletic group. Finally, this study included 62 male and female athletes, divided into two groups of different sports specializations. The detailed characteristics are presented in Table tively different metabolic and physiological profiles and had the same training status. The endurance group consisted of long-distance runners (specializing in 5 and 10 km) and triathletes (specializing in 1.5 km swimming, 40 km cycling, and 10 km running), whose competitive effort mainly involved low- to moderate-intensity activity. The speed-power group comprised sprinters (competing in the 60–200 m distances) and Olympic taekwondo athletes, who predominantly engaged in high-intensity explosive activities during training and competition. Both groups competed at
runners (specializing in 5 and 10 km) and triathletes (specializing in 1.5 km swimming, 40 km cycling, and 10 km running), whose competitive effort mainly involved low- to moderate-intensity activity. The speed-power group comprised sprinters (competing in the 60–200 m distances) and Olympic taekwondo athletes, who predominantly engaged in high-intensity explosive activities during training and competition. Both groups competed at the national level.
J. Clin. Med.2024,13, 4812 3 of 15 Table 1.The basic characteristics of the athletic groups and the differences between male and female athletes. Endurance Speed-Power Male Female Male Female Age (y) 23 ±7 20 ±2 21.1 ±2.6 20 ±3 Height (cm) 179±6 # 165.1±4.2 182.1±5.4 # 171.1±9 BM (kg) 68±6.6 # * 54±4.4 † 78±9.4 # 62.9±11 BF (kg) 9.0 ±2.5 11.7±1.8 † 12.4±4.0 15.8 ±5.9 BF (%) 13.2±3 # * 21.8±3.6 † 15.9±4.8 # 24.5±5 SMM (kg) 29.9±3.2 # * 20.3±2.3 † 34.6±5 # 24±3.6 SMM (%) 43.9±1.4 # 37.6±1.9 44.2±2.8 # 38.3±2.1 LLM (kg) 19.6±2.1 # * 13.8±1.7 † 22.6±3.1 # 16.5±3 LLM (%) 81.7±3 # 70.5±4 79.7±5 # 69.5±5 LA REST(mmol/L) 2.2 ±0.6 2.1 ±0.6 2.3 ±0.6 2.2 ±0.5 LA PEAK(mmol/L) 7.8±1.1 # * 6.9±1.8 † 9.6±1.7 8.7 ±1.6 Values are expressed as means±standard deviations (p< 0.05). Abbreviations: BM—body mass; BF—body fat; SMM—skeletal muscle mass; LLM—leg lean mass; LAREST—lactate concentration at rest; and LAPEAK—lactate concentration at peak. # Significantly different from female athletes within the same group. * Significantly different between male athletic groups. † Significantly different between female athletic groups. 2.2. Procedures The tests were conducted immediately after the transition (detraining) phase in the general preparation of the annual training cycle of the athletes. A week before the main examination, athletes participated in a familiarization session to acquaint themselves with the procedures and testing protocols. This study took place in the Human Movement Laboratory of the Department of Athletics and Strength and Conditioning at the Poznan University of Physical Education. The project was granted by the Ethics Committee at the Poznan University of Medical Sciences on 9 September 2020 (decision no. 627/20), and the research was carried out according to the principles of the Helsinki Declaration. All participants were familiarized with the study’s aim, procedures, and potential risks and signed the informed consent. To ensure accurate test results, athletes were instructed to be fast before undergoing the body composition analysis and to avoid high-intensity or long-duration training sessions for at least 24–48 h before testing. The blood samples were obtained before and after the Wingate test.
All participants were familiarized with the study’s aim, procedures, and potential risks and signed the informed consent. To ensure accurate test results, athletes were instructed to be fast before undergoing the body composition analysis and to avoid high-intensity or long-duration training sessions for at least 24–48 h before testing. The blood samples were obtained before and after the Wingate test. Throughout the survey, the room temperature was maintained at 20–21 ◦ C. The procedures are shown in Figure subsequent sections.J. Clin. Med. 2024, 13, x FOR PEER REVIEW 4 of 16 Figure 1. Testing procedure. The graph was created using Canva. 2.3. Body Composition Analysis A digital stadiometer (SECA 285, Hamburg, Germany) was employed to measure height and weight. Body composition analysis was performed using the Lunar Prodigy Pro device (GE Healthcare, Madison, WI, USA) and enCORE v16 SP1 software through the Dual X-ray Absorptiometry (DXA) method. The DXA scans were obtained and analyzed according to the protocol proposed by Nana [17]. The calculation of the total- body SMM was followed by the method proposed by Kim [18]. 2.4. Wingate Test The Wingate test was carried out according to standardization guidelines [19] using the Cyclus 2 cycle ergometer (RBM elektronik-automation GmbH, Leipzig, Germany). The test began with a 5-minute warm-up, wherein participants pedaled at their own pace with resistance loads of 25 and 50 W, interspersed with brief sprints lasting up to 5 s. Then, after a ~2-minute rest period, athletes were instructed to cycle as fast as they could for 15 s. To commence the test, participants were required to have a blood lactate concentration below 3 mmol·L −1 . If the level was higher, the test start was postponed until the desired value was achieved. The resistance load was set at 0.085 and 0.075 kg per kg of body weight for male and female athletes, respectively [20]. Throughout the test, participants received verbal encouragement to perform at their best. After completing the test, participants remained seated for a minimum of 10 min. Peak power was defined as the highest mechanical power achieved in a 5-second segment of the
was set at 0.085 and 0.075 kg per kg of body weight for male and female athletes, respectively [20]. Throughout the test, participants received verbal encouragement to perform at their best. After completing the test, participants remained seated for a minimum of 10 min. Peak power was defined as the highest mechanical power achieved in a 5-second segment of the test, while mean power was calculated by averaging the instantaneous power values over the 15-second test duration. The fatigue index, indicating the rate of power decline, was determined by subtracting the maximum and minimum output power values and dividing the difference by the time of power drop [21,22]. 2.5. Oxygen Uptake and Lactate The respiratory parameters were recorded by MetaMax 3B-R2, and the subsequent analysis was conducted using MetaSoft Studio Software 5.1.0 (both: Cortex Biophysik GmbH, Leipzig, Germany). Measurements were recorded 5 min before (to determine resting V̇ O 2), continuously during the test, and 10 min after its completion. For lactate concentration determination, blood samples were obtained from the fingertip at three specific intervals: at rest, after the warm-up phase, and every minute in the period between the 3rd and the 10th minute following the test. The analysis was based on the resting and peak post-exercise values. The Biosen C-line apparatus (EKF Diagnostic GmbH in Barleben, Germany) was used to measure lactate levels utilizing capillary whole blood samples. Figure 1.Testing procedure. The graph was created using Canva. 2.3. Body Composition Analysis A digital stadiometer (SECA 285, Hamburg, Germany) was employed to measure height and weight. Body composition analysis was performed using the Lunar Prodigy Pro device (GE Healthcare, Madison, WI, USA) and enCORE v16 SP1 software through the
J. Clin. Med.2024,13, 4812 4 of 15 Dual X-ray Absorptiometry (DXA) method. The DXA scans were obtained and analyzed according to the protocol proposed by Nana [17]. The calculation of the total-body SMM was followed by the method proposed by Kim [18]. 2.4. Wingate Test The Wingate test was carried out according to standardization guidelines [19] using the Cyclus 2 cycle ergometer (RBM elektronik-automation GmbH, Leipzig, Germany). The test began with a 5-min warm-up, wherein participants pedaled at their own pace with resistance loads of 25 and 50 W, interspersed with brief sprints lasting up to 5 s. Then, after a ~2-min rest period, athletes were instructed to cycle as fast as they could for 15 s. To commence the test, participants were required to have a blood lactate concentration below 3 mmol·L −1 . If the level was higher, the test start was postponed until the desired value was achieved. The resistance load was set at 0.085 and 0.075 kg per kg of body weight for male and female athletes, respectively [20]. Throughout the test, participants received verbal encouragement to perform at their best. After completing the test, participants remained seated for a minimum of 10 min. Peak power was defined as the highest mechanical power achieved in a 5-s segment of the test, while mean power was calculated by averaging the instantaneous power values over the 15-s test duration. The fatigue index, indicating the rate of power decline, was determined by subtracting the maximum and minimum output power values and dividing the difference by the time of power drop [21,22]. 2.5. Oxygen Uptake and Lactate The respiratory parameters were recorded by MetaMax 3B-R2, and the subsequent analysis was conducted using MetaSoft Studio Software 5.1.0 (both: Cortex Biophysik GmbH, Leipzig, Germany). Measurements were recorded 5 min before (to determine resting˙VO2), continuously during the test, and 10 min after its completion. For lactate concentration determination, blood samples were obtained from the fingertip at three specific intervals: at rest, after the warm-up phase, and every minute in the period between the 3rd and the 10th minute following the test. The analysis
Leipzig, Germany). Measurements were recorded 5 min before (to determine resting˙VO2), continuously during the test, and 10 min after its completion. For lactate concentration determination, blood samples were obtained from the fingertip at three specific intervals: at rest, after the warm-up phase, and every minute in the period between the 3rd and the 10th minute following the test. The analysis was based on the resting and peak post-exercise values. The Biosen C-line apparatus (EKF Diagnostic GmbH in Barleben, Germany) was used to measure lactate levels utilizing capillary whole blood samples. 2.6. Calculation of the Energy System Contribution The PCr-LA-O2method was used to evaluate the contributions of the aerobic, gly- colytic, and phosphagen energy systems as described by Beneke and Bertuzzi [23–25]. Energy expenditure for these systems was quantified in kilojoules, assuming a caloric equivalent of 20.9 kJ per 1 L of O2. Energy derived from the aerobic system (EAER) was determined by subtracting the resting˙VO2(5 min) from the˙VO2recorded during maximal exercise, employing the trapezoidal method [23]. Energy from the glycolytic system (ELA) was assessed using the oxygen equivalent derived from blood lactate concentration. This was approximated as the difference between peak lactate concentration and resting lactate levels. A net value of 1 mmol·L −1 was equated to 3 mL O2·kg body mass −1 [26]. Energy from the phosphagen system (EPCR) was calculated based on the fast component of the excess post-exercise oxygen consumption (EPOC) [27]. The˙VO2consumption data were collected during a 10-min recovery period after the test, following procedures outlined in the study [28], and calculated using the bi-exponential model [29]. The subsequent formulas were applied: ˙VO 2(t)=˙VO 2baseline+ A f[e −(t-td)/τ f] + As[e −(t-td)/τ s] EPCR =A f·τ f, where˙VO 2(t)is the oxygen uptake at timet;˙VO 2baselineis the oxygen uptake at rest; A is the amplitude; td is the time delay;τis the time constant;fdenotes the fast; andsdenotes the slow component of EPOC. To achieve an accurate fit for each EPOC kinetic curve, we
oxygen uptake at rest; A is the amplitude; td is the time delay;τis the time constant;fdenotes the fast; andsdenotes the slow component of EPOC. To achieve an accurate fit for each EPOC kinetic curve, we
J. Clin. Med.2024,13, 4812 5 of 15 conducted calculations at various time points of oxygen consumption, from the 3rd to the 10th minute of recovery. Due to consistently reliable outcomes, we specifically focused on the7-minEPOC period in our analysis. This approach yielded high coefficients of determination for all the kinetic curves assessed (r 2 = 0.80–0.98). Our approach to analyz- ing EPOC aligns with methodologies adopted in other studies, which typically involve assessing recovery time from the 6th to the 10th minute following various high-intensity ex- ercises such as the 100 m sprint and 15- or 30-s all-out cycling efforts [30–33]. Furthermore, Bertuzzi et al. [28] argued that monitoring the initial 6 min of˙VO2recovery post moderate- and high-intensity exercise adequately reveals the contribution of the phosphagen sys- tem. Additionally, we edited the raw data according to the methods proposed by Lamara and Myers [34,35]. Consequently, values exceeding 3 standard deviations were omitted to exclude deviations potentially caused by coughing, sighing, etc. The data underwent analysis using the GEDAE-LaB software (first version available on GitHub.com), devel- oped by researchers from Sao Paulo University and the Federal University of Pernambuco, Brazil [28]. The total energy expenditure (E TOT) was calculated as follows: ETOT= EAER+ ELA+ EPCR The proportion of each energy system was calculated as a percentage of (ETOT). 2.7. Statistical Analyses The normality of the data distribution was tested using the Shapiro–Wilk test. As the dis- tribution was found to be normal, all values were shown as the mean and standard deviation. A multivariate analysis of variance (MANOVA) was performed to test the effects of group, sex, and their interaction on the set of dependent variables (energy from three systems). Following this, a two-way analysis of variance (ANOVA) was conducted for each dependent variable (energy system) to further examine the effects of group, sex, and their interaction. Also, an analysis of covariance (ANCOVA) was performed to account for the variables BF and SMM. In addition, a one-way ANOVA was conducted to assess the magnitude of the differences in descriptive variables among athletic groups between males and females. The Levene’s test was
Description
The study investigates sex differences in energy system contributions during sprinting.