Abstract
This research examines the effects of a 12-week High-Intensity Interval Training (HIIT) program on VO2 max and blood lactate concentrations in elite boxers, utilizing treadmill and Cosmed K5 assessment techniques. The study involving twenty elite male boxers demonstrated significant improvements in VO2 max (p < 0.01) for both techniques, with the Cosmed K5 exhibiting a greater relative increase of 13.4% compared to the treadmill's 8% increase. Blood lactate levels increased progressively over three simulated rounds, from 54.33 to 61.4 mmol/L, highlighting the role of anaerobic metabolism. This research evaluates how well the two different protocols systems measure VO2 max after high-intensity interval training (HIIT). Results: Statistical analysis demonstrated the superiority of Cosmed K5 in identifying training-induced changes (p = 0.002). In conclusion, the Cosmed K5 serves as a dependable and effective instrument for evaluating aerobic capacity within sport-specific environments, thereby increasing its value for coaches and athletic programs. Keywords: VO2 max, High-Intensity Interval Training, Boxing; Treadmill, Cosmed K5/VO2 máximo, HIIT, INTRODUCTION Exercise is recognized as a key component in increasing energy expenditure, as shown by oxygen uptake measurements. (Vianna et al., 2011). Regular exercise is recognized for its ability to enhance health and diminish various risk factors associated with chronic diseases (Myers et al., 2015). Boxing is a sport that necessitates both dynamic and static attributes (Evrim et al., 2019). Resistance training (RT) serves as an effective stimulus for the neuromuscular system, promoting muscle
by oxygen uptake measurements. (Vianna et al., 2011). Regular exercise is recognized for its ability to enhance health and diminish various risk factors associated with chronic diseases (Myers et al., 2015). Boxing is a sport that necessitates both dynamic and static attributes (Evrim et al., 2019). Resistance training (RT) serves as an effective stimulus for the neuromuscular system, promoting muscle hypertrophy and strength development (Ozaki et al., 2013), and is recognized for its beneficial health effects (Paoli et al., 2017).
Marsida Bushati 1* , Orkida Kosta 2 , Sead Bushati 2 ________________________________________________________________________________________________________________________________________________ 254 Aerobic capacity, quantified by maximal oxygen uptake (VO2 max), is fundamental to physiological performance in combat sports such as boxing, where athletes perform high-intensity intermittent efforts with short recovery intervalsThe ability to sustain performance over several rounds depends on effective energy metabolism, rapid recovery, and efficient oxygen utilization—all of which are influenced by VO2 max (Bacon et al., 2013).Lactate is a by-product of anaerobic metabolism, often associated with muscle fatigue during high-intensity exercise. It has long been a subject of interest for athletes and sports scientists, especially in disciplines that involve explosive and sustained physical efforts, such as boxing. This article aims to explore how lactate levels in blood affect boxers’ performance and recovery, considering both physiological mechanisms and practical implications for training. High-Intensity Interval Training (HIIT) involves alternating short bursts of maximal effort with periods of rest or low-intensity recovery. This training modality has proven effective in enhancing both aerobic and anaerobic capacities, rendering it especially beneficial for boxers (Laursen & Jenkins, 2002). The optimal method for assessing VO2 max in sport- specific contexts is still debated. Conventional VO2 max evaluations depend on laboratory treadmill or cycle ergometer tests, offering high accuracy yet constrained by their controlled settings. (Belts, N., M., et al., 2016) The tests frequently do not replicate the dynamic, multiplanar movements characteristic of boxing, including punching, footwork, and defensive maneuvers, which diminishes their ecological validity (Vianna et al., 2011). Portable metabolic systems, exemplified by the Cosmed K5, have transformed field-based testing by providing real-time physiological data in natural settings, effectively connecting laboratory precision with practical use (Romero-Caballero et al., 2022). The Cosmed K5 features a lightweight design and breath-by-breath gas analysis, enabling assessments during real training or simulated sessions, thus offering a viable alternative to stationary systems. This study also analyzes blood lactate levels as an additional measure of anaerobic contribution, providing a comprehensive view of the physiological adaptations induced by HIIT. The research hypothesis suggests that the Cosmed K5 will exhibit enhanced sensitivity to training-induced changes owing to its sport-specific applicability, potentially
during real training or simulated sessions, thus offering a viable alternative to stationary systems. This study also analyzes blood lactate levels as an additional measure of anaerobic contribution, providing a comprehensive view of the physiological adaptations induced by HIIT. The research hypothesis suggests that the Cosmed K5 will exhibit enhanced sensitivity to training-induced changes owing to its sport-specific applicability, potentially yielding more profound insights into aerobic capacity in boxing. Jacob, N. (2022). MATERIAL AND METHODS Methodology Participants The research involved 30 elite male amateur boxers with an average age of 22.8 ± 3.6 years, sourced from the national team's competitive programs. Participants were chosen for their significant competitive experience (at least 5 years) and current training status, thereby creating a uniform sample of high-performance athletes. Exclusion criteria comprised recent musculoskeletal injuries, cardiovascular conditions, or any contraindications to maximal exercise testing, as established through a pre-study medical screening performed by university health professionals. All participants provided written informed consent, and the study protocol received approval from the Institutional Ethics Committee of the Sports University of Tirana, adhering to the principles outlined in the Declaration of Helsinki. . Study Design The study was conducted in the Physiology Laboratory of the UST- Albania, and all data were recorded using its licensed equipment. The primary apparatuses employed for the examination of endurance performance were: • Treadmill T200M Cosmed; • Cosmed K5; • Lactate meter (Lactate Scout 4); • Testing Protocols (Procedure); • Treadmill Protocols; The boxers will first engage in a standard warm-up in the gym for approximately 30-35 minutes. Following this, they will proceed to the laboratory to begin testing on the treadmill. During the initial 3 minutes, they will where the speed is gradually increased every 15–30 seconds to reach VO₂ max in ~8–12 minutes. (Vianna et al., 2011The objective is to evaluate boxers' VÇO2 max and HRmax. The temperature was the same in both protocols, 27 degrees.
International Journal of Ecosystems and Ecology Science (IJEES) Vol. 15 (3): 253-260 (2025) https://doi.org/10.31407/ijees https://doi.org/10.31407/ijees15.3 255 Cosmed K5 Protocols The two research groups will undergo testing at the commencement and conclusion of the study. The evaluation will take place during a training session that commences with the participants' daily warm-up, which typically lasts for thirty to thirty-five minutes. The Fitmate Pro device will be connected to the headgear, and the evaluation will commence. It will be divided into three stages, each of which will last for three minutes, with a one-minute intermission to simulate the conditions of a match. The boxer will respond to the trainer's instructions by grasping the paddles and commencing the semi-contact simulated boxing sequence upon receiving the signal. While at leisure, the boxer will maintain a stance reminiscent of a boxing match. The gym location where the test will be administered must maintain a temperature and relative humidity within the range of 27.0C, as per the training approach. Blood Lactate Measurement Post-round blood lactate levels were assessed during a three-round simulated bout, consisting of three minutes per round with one-minute rest intervals, utilizing a portable lactate analyzer (Lactate Scout 4). Capillary blood samples were obtained from the fingertip promptly following each round, serving as an immediate measure of anaerobic metabolism. Measurements were conducted in triplicate to guarantee reliability, with averages duly reported. High-Intensity Interval Training Program The experimental group employs the Continuous Method, characterized by the uninterrupted application of physical-motor actions over extended durations and at a comparatively moderate pace. This approach was formulated through various running techniques, tailored to the nuances of the boxing discipline: • A gradual running mode: wherein the training session extended for 45-50 minutes, maintaining a heart rate of 145- 150 beats per minute. • Engaged in a moderate tempo; the training session spanned 20-30 minutes, with a heart rate maintained at 150-170 beats per minute. • A briskly conducted session: wherein the training duration spans 20-30 minutes, maintaining a pulse rate of 160- 165 beats per minute. Running segments with different lengths and speeds were used to implement the intervalor
beats per minute. • Engaged in a moderate tempo; the training session spanned 20-30 minutes, with a heart rate maintained at 150-170 beats per minute. • A briskly conducted session: wherein the training duration spans 20-30 minutes, maintaining a pulse rate of 160- 165 beats per minute. Running segments with different lengths and speeds were used to implement the intervalor approach, which was customized to the boxer's physical condition and preferences. The organization was mostly set up in two different ways that matched boxing's requirements: • With significant duration: ranging from 50 to 60 minutes; with a pulse rate of 140 to 150 beatsperminute. • With a duration of 30-40 minutes, accompanied by a heart rate of 160-170 beats per minute. Hipoksing training was organized as a purposeful preparatory method meant to improve endurance under certain time constraints and special circumstances, especially at high elevations above sea level. Statistical Analysis The analysis of data was conducted utilizing SPSS version 26, employing paired t-tests to compare VO2 max values before and after the intervention within each method, alongside independent t-tests to evaluate the differences between the methods. The analysis of correlation examined the interplay between VO2 max and average lactate concentrations. The threshold for significance was established at α = 0.05, while effect sizes were determined through Cohen’s d to measure the extent of training effects. RESULTS VO2 Max Improvements Post-HIIT, VO2 max increased significantly with both methods. The treadmill test recorded a rise from 54.97 ± 4.2 ml/kg/min to 59.75 ± 4.8 ml/kg/min, representing an 8.7% improvement (t = 6.32, p < 0.01). The Cosmed K5 test showed a more substantial increase from 47.16 ± 3.9 ml/kg/min to 54.51 ± 4.5 ml/kg/min, a 13.4% enhancement (t = 8.45, p < 0.01). An independent t-test revealed a significant difference in the magnitude of improvement between the two methods (t = 3.101, p = 0.002), with the Cosmed K5 demonstrating greater sensitivity to training-induced changes as of the analysis conducted on 11:23 AM CEST, Saturday, June 14, 2025.
0.01). An independent t-test revealed a significant difference in the magnitude of improvement between the two methods (t = 3.101, p = 0.002), with the Cosmed K5 demonstrating greater sensitivity to training-induced changes as of the analysis conducted on 11:23 AM CEST, Saturday, June 14, 2025.
Marsida Bushati 1* , Orkida Kosta 2 , Sead Bushati 2 ________________________________________________________________________________________________________________________________________________ 256 1 2 Figure 1 and 2. VO2 Max Improvements Pre- and Post-HIIT, Blood Lactate. This bar chart delineates the VO2 max values obtained through the treadmill and Cosmed K5 methods, both prior to and following the intervention. The x-axis delineates the testing phase, encompassing both Pre-Test and Post-Test, whereas the y-axis illustrates VO2 max measured in ml/kg/min. The treadmill data, represented by the red bars, demonstrates an increase from 54.97 ml/kg/min to 59.75 ml/kg/min, reflecting an 8.7% enhancement. The data for the Cosmed K5, represented by teal bars, demonstrates an increase from 47.16 ml/kg/min to 54.51 ml/kg/min, indicating a 13.4% improvement. The chart elucidates the significant enhancement observed with the Cosmed K5, as its post-test value nears that of the treadmill, thereby emphasizing its responsiveness to sport-specific adaptations. (To replicate this chart in Word, employ a clustered bar chart featuring two series: Treadmill and Cosmed K5, utilizing the data presented in Table 1.) Blood Lactate Levels The levels of blood lactate increased throughout the simulated bouts: 54.33 ± 5.1 mmol/L following Round 1, 59.06 ± 5.8 mmol/L after Round 2, and 61.4 ± 6.2 mmol/L post Round 3, reflecting a progressive anaerobic demand (F = 12.34, p < 0.01 for Round 1 compared to Round 3). This development illustrates the growing dependence on glycolytic pathways as the session progressed, a trend that aligns with the intermittent characteristics of boxing. Blood Lactate Levels Across Simulated Rounds This line chart illustrates the average blood lactate concentrations observed throughout three simulated rounds of boxing. The x-axis delineates the rounds (Round 1, Round 2, Round 3), whereas the y-axis signifies lactate concentrations measured in mmol/L. The data points—54.33 mmol/L for Round 1, 59.06 mmol/L for Round 2, and 61.4 mmol/L for Round 3—are interconnected by a blue line, illustrating a consistent upward trajectory that signifies an escalation in anaerobic effort. The chart highlights the gradual increase in metabolic stress throughout the duration of the bout. (To reproduce this chart in Word, employ a line chart featuring a single series: Blood Lactate,
1, 59.06 mmol/L for Round 2, and 61.4 mmol/L for Round 3—are interconnected by a blue line, illustrating a consistent upward trajectory that signifies an escalation in anaerobic effort. The chart highlights the gradual increase in metabolic stress throughout the duration of the bout. (To reproduce this chart in Word, employ a line chart featuring a single series: Blood Lactate, utilizing the data presented in Table 5.) Correlation Analysis The correlation coefficients observed between mean lactate levels and VO2 max were found to be weak and statistically non-significant: r = 0.03 (p > 0.05) for the treadmill, and r = -0.21 (p > 0.05) for the Cosmed K5. This indicates that aerobic and anaerobic capacities embody separate physiological realms, lacking a robust linear correlation within this group. Effect Sizes The effect sizes highlighted the influence of the training, with Cohen’s d values of 0.87 for the treadmill and 1.21 for the Cosmed K5, suggesting a substantial effect for the latter. This underscores the Cosmed K5’s exceptional capacity to identify significant physiological changes.
International Journal of Ecosystems and Ecology Science (IJEES) Vol. 15 (3): 253-260 (2025) https://doi.org/10.31407/ijees https://doi.org/10.31407/ijees15.3 257 Table 1. Comparison of VO2 Max Pre- and Post-Training. Method Pre-Test Mean Post-Test Mean Improvement (%) Treadmill 54.97 ml/kg/min 59.75 ml/kg/min 8.0% Cosmed K5 47.16 ml/kg/min 54.51 ml/kg/min 13.4% Both methods show significant improvements in VO₂ max, which is an indicator of increased cardiovascular and aerobic efficiency. An increase in VO₂ max of 8–13% is very significant and can translate into increased endurance, aerobic capacity, and sports performance. These data support the effectiveness of a 12-week exercise training program Table 2. Percentage Change in VO₂ max. Method Change (%) Treadmill 8.7% Cosmed K5 13.4% Table 3. Effect Size (Cohen’s d). Method Cohen's d Treadmill 0.87 Cosmed K5 1.21 Table 4. Independent Samples t-Test. Comparison t-value p-value Post VO₂ max (Treadmill vs K5) 3.101 0.002 Table 5. Blood Lactate Levels After Each Round (mmol/L). Raundi Pre-Test (mmol) Post-Test (mmol) Ndryshimi Raundi 1 54.33 50.01 -4.32 (↓) Raundi 2 59.60 53.36 -6.24 (↓) Raundi 3 61.40 57.24 -4.16 (↓) All values decreased after the test, indicating an improvement in the ability to manage or metabolize lactate as a result of the HIT training method. The largest decrease was in the second round (-6.24 mmol), indicating that the athletes began to better cope with the intensity during the middle phase of the load. Table 6. Correlation Between VO₂ max and Mean Lactate. Method Correlation (r) p-value Treadmill 0.03 > 0.05 Cosmed K5 -0.21 > 0.05 Discussion VO2 Max Enhancements The notable enhancements in VO2 max following high-intensity interval training correspond with a substantial body of research regarding the effectiveness of interval training in augmenting aerobic capacity (Weston et al., 2014). The 8.7% increase observed through treadmill testing indicates a notable enhancement in cardiovascular efficiency, presumably influenced by an augmented stroke volume and a more effective oxygen extraction by skeletal muscles (Coyle, 1995). The notable 13.4% enhancement observed with the Cosmed K5 indicates a superior level of adaptation, likely due to its tailored sport-specific protocol. The K5 test's dynamic characteristics, integrating boxing-specific actions such as punching and footwork,
indicates a notable enhancement in cardiovascular efficiency, presumably influenced by an augmented stroke volume and a more effective oxygen extraction by skeletal muscles (Coyle, 1995). The notable 13.4% enhancement observed with the Cosmed K5 indicates a superior level of adaptation, likely due to its tailored sport-specific protocol. The K5 test's dynamic characteristics, integrating boxing-specific actions such as punching and footwork, may have more effectively engaged the neuromuscular and
Marsida Bushati 1* , Orkida Kosta 2 , Sead Bushati 2 ________________________________________________________________________________________________________________________________________________ 258 metabolic pathways pertinent to competition, thereby underscoring its ecological validity. Figure 1 provides a visual affirmation of these trends, with the Cosmed K5 exhibiting a more pronounced upward trajectory. Blood Lactate Dynamics The incremental increase in blood lactate levels firs test (from 54.33 to 61.4 mmol/L) throughout the simulated bouts suggests an escalating dependence on anaerobic glycolysis as the exertion persisted, a phenomenon that is well- established in the realm of combat sports (Ghosh, 2004). The absence of a noteworthy correlation with VO2 max (r = 0.03 and -0.21) reinforces the proposition that aerobic and anaerobic systems function as separate yet interrelated realms. Figure 2 demonstrates this consistent upward trend, highlighting the anaerobic demand that HIIT training presumably alleviated via enhanced buffering capacity. And in the second test all values decreased after the test, indicating an improvement in the ability to manage or metabolize lactate as a result of the HIT training method. The largest decrease was in the second round (-6.24 mmol), indicating that the athletes began to better cope with the intensity during the middle phase of the load. Methodological Considerations The exceptional performance of the Cosmed K5 likely arises from its capacity to record real-time physiological responses during functional movements, thereby minimizing the artificiality associated with treadmill testing. Prior research has confirmed the K5’s precision when compared to stationary systems, demonstrating correlation coefficients that surpass 0.95 (Romero-Caballero et al., 2022). The elevated effect size (1.21 compared to 0.87) reinforces its sensitivity; however, factors such as mask comfort, movement artifacts, and environmental conditions (for instance, ring temperature) necessitate additional investigation. The meticulously regulated environment of the treadmill assessment established a consistent baseline; however, its failure to emulate the complexities of boxing dynamics could elucidate the diminished observed enhancement. Physiological Mechanisms The improvements in VO2 max associated with HIIT are probably attributable to a blend of central adaptations, such as increased cardiac output and capillary density, alongside peripheral adaptations, including enhanced mitochondrial function and oxidative enzyme activity (Santos-Concejero et al., 2014). The enhanced response observed with