Sports such as soccer, basketball, and tennis, among others require athletes to perform a range of dynamic and explosive activities from power jumping (e.g., dunk in basketball) to long sprints (e.g., soccer). The intermittent nature of these sports means that athletes often have to produce power in a metabolically fatigued state (4). Thus, the quality of performance in these types of events is often dependent on the body's ability to optimally use all available energy resources and maintain homeostasis. The body's capacity for storage of adenosine triphosphate (ATP) is limited. Various metabolic pathways supply ATP at different stages of activity and the generation of metabolic energy results in the production of chemical biproducts such as lactate (7,11).
Lactate formation occurs as a response to increased energy demand and reduced availability of oxygen. Lactate clearance occurs via the use of lactate as an energy source. When energy demand exceeds aerobic capacity and lactate production exceeds clearance, lactate accumulates (8). Lactate accumulation and the associated build up of H+ is 1 cause of muscular fatigue (11,27). Ideally then, continuous and concurrent lactate clearance should offset production to ensure that the concentrations of blood lactate and H+ do not exceed the rate of lactate use.
There are generally 3 conditioning goals in relation to lactate: (a) to reduce production by improving the ability to use aerobic metabolism for longer durations and at higher intensities, (b) to increase the ability of the various organs to use and manage lactate, and (c) to increase lactate tolerance—in other words, to increase the ability of muscle to function at elevated lactate levels. To achieve these 3 goals, athletes must work at or above their lactate threshold—the point at which lactate accumulation accelerates in a nonlinear fashion (12,27,36). A second point of lactate accumulation occurs at a slightly higher intensity and is known as onset of blood lactate accumulation (OBLA). Previous studies have noted that OBLA occurs at lactate concentrations of ≥4 mmol·L−1 (36,38). The point at which lactate production and clearance is in the state of equilibrium is known as maximum lactate steady state (MLSS) (5). Training practices to improve lactate tolerance and clearance should include activities at or above OBLA, aimed at prolonging MLSS.
Current training practices for improving lactate tolerance and clearance in athletes involve predominantly aerobic activities (11,15). Clark and Edwards observed a rightward shift in the inflection points on the lactate curve at the end of 5 weeks of aerobic conditioning and at the end of the competitive soccer season when compared to the beginning of the season (10). However, improvement in lactate tolerance and clearance through aerobic conditioning may have subsequent physiological adaptations that can be detrimental to other important conditioning parameters such as power, muscle girth, and size, which can eventually affect athletic performance (14,29). A season long body composition study conducted using female soccer players indicated an increased mean fat percentage from 16.24% at the beginning to 18.78% at the end of the season. Body weight decreased despite the increase in fat mass, which is a clear indication of the loss of lean mass that was accompanied by a decrease in aerobic capacity (25). Primary reasons for these negative effects may include lack of resistance training during the season because of time constraints and the use of tapering. In addition to sports performance limitations, any loss of muscle mass may result in muscle imbalance, which in turn, could lead to musculoskeletal injury (18). Thus, it is important to evaluate training practices that promote improvements in lactate clearance and tolerance while minimizing the undesirable physiological adaptations such as loss of strength and power, which are associated with detraining or excessive aerobic conditioning.
Dynamic, explosive activities such as jumping and sprinting in intermittent field sports such as soccer and basketball predominantly recruit type II muscle fibers to produce power (32). The muscle fibers of intermediate and large motor units used in explosive power and resistance training activities produce more lactate than small motor units do; similarly, type II muscle fibers have shown greater glycolytic enzyme activity and hence a greater ability to produce lactate. Lactate production is greater in high-intensity, intermittent activities associated with anaerobic energy pathways and explosive power production compared with low-intensity, continuous activities (24). This interaction between lactate production and power production abilities and intermittent yet intense nature of sports such as soccer means that athletes often have to produce power in the presence of lactate. Previous studies have reported a 4- to 10-minute time range for cellular lactate effusion (34). This means that explosive power activities performed within the aforementioned time range can elicit increased lactate production. Therefore, it is possible that performing explosive training for a longer time than is currently stipulated might improve lactate tolerance.
Type I muscle fibers possess greater aerobic capacity and ability to use lactate as an energy source because of their greater mitochondrial volume density and aerobic enzyme content (22). Previous work has demonstrated higher lactate clearance rates during aerobic activities (9). In addition, exposure to high lactate can improve lactate-buffering capacity (26). However, endurance training is shown to affect only lactate clearance, not production (13). Paton and Hopkins indicated that a combination of explosive training and high-volume (HV) resistance training may assist in improving lactate clearance (30). As discussed before, prolonging MLSS and working at an intensity slightly above the OBLA are important determinants to improve the lactate clearance mechanism. However, previous studies have suggested that OBLA and MLSS may be dependent on motor patterns of activity and may be a function of the relationship between power output and working muscle mass (6). This indicates that lactate concentrations >4 mmol·L−1 achieved through explosive power training, which provides greater power output and recruits greater muscle mass, may effectively overload the lactate clearance mechanism.
Therefore, it is possible that training for improvement in lactate clearance might consist of pairing intense explosive power activities to produce lactate and overload the lactate clearance mechanism with light aerobic activity to clear the accumulated lactate.
Olympic weight lifting movements (Olympic lifts) are common explosive training tools in current strength and conditioning practices (e.g., supplementary exercises to competitive Olympic weight lifting such as the clean, jerk, push jerk, and clean pull, among others). All of the aforementioned lifts are explosive, anaerobic movements, with the potential for lactate production, if performed in sufficient volumes. The use of the Olympic lifts for athletic conditioning typically incorporates volume patterns of 1–6 repetitions (reps). This arises from the belief that (a) Olympic lifts should be used to improve explosive power and nothing else, and (b) it is difficult to maintain correct technique during sets of >6 reps and this may increase injury risk. However, to our knowledge, no research study has supported this belief. Field athletes often produce power in training with a fresh nervous system and with minimal kinetic chain limitations; however, the ability to maintain explosiveness while fatigued is also an important performance element for intermittent field sports (4). To date, researchers have not investigated more intense training pattern for power-oriented intermittent sports. If more can be learned about the manipulation of sets and reps during Olympic lifts, and how it might impact lactate profile, and ultimately lactate threshold, athletes in power-oriented intermittent sports may consider a training intervention such as high volume (HV) Olympic lifts to improve lactate clearance and tolerance.
Unfortunately, few studies have evaluated whether the physiological response to Olympic lifts are similar to nonexplosive resistance training in regards to lactate production (19). Limited data currently available warrant further research in this area before considering Olympic lifts as a potential training protocol for improving lactate tolerance and clearance.
Experimental Approach to the Problem
Given the lack of data examining the effects of Olympic lifts on blood lactate, the purpose of this study was to use a cross-sectional design to evaluate the effects of 3 different volume patterns (3, 6, and 9 reps) of power cleans on blood lactate concentrations immediately after exercise. We hypothesized that the greater volume of the power cleans would generate greater lactate production. The independent variables selected for this study were the 3 volume patterns. Three sets were performed for each rep range. The number of sets was determined according to common norms and guidelines of current conditioning practices (16,17). The dependent variable selected for this study was lactate response because this study was designed to determine if there was a difference in lactate response among the 3 aforementioned volume patterns.
Ten male recreational athletes (i.e., athletes who were active in recreational and lower level competitive sports) (24.22 ± 1.39 years, 87. 7 ± 11.5 kg, 184.2 ± 8.7 cm) completed an IRB approved informed consent form and volunteered for the study. The subjects were recruited through word of mouth and campus flyers. The subjects had a minimum of 1 year of prior Olympic lifting experience and were evaluated for Olympic lift technical proficiency as per National Strength and Conditioning Association (NSCA) Guidelines (2) before the commencement of the study. Nutritional status of the subjects was not monitored.
Selection of Power Cleans
As was specified in the previous section, common movements in Olympic lifts include the clean, the snatch, push jerk, and clean pull (2). The power clean was selected as the exercise of choice in this study because previous research has observed greater lactate production in the clean and jerk (which includes power clean as one of the phases of entire movement) compared with the snatch (19). In addition, variations of cleans are more commonly used in athletic conditioning, and it is the belief of the authors that it is easier to maintain proper technique with cleans than with the clean and jerk or with the snatch. Finally, greater loads can be lifted in power cleans as compared with hang cleans, which may result in greater lactate response.
Three volume patterns were selected in this study. The low-volume (LV) pattern consisted of 3 sets × 3 reps, the midvolume (MV) pattern consisted of 3 sets × 6 reps, and the HV pattern consisted of 3 sets × 9 reps. Each volume pattern was performed on a different day with a minimum of 48 hours of rest between 2 sessions. The participants performed LV on day 1, MV on day 2, and HV on day 3.
To determine the intensity of the aforementioned workloads, the repetition maximum (RM) method was used (23). The NSCA recommended estimated association between numbers of reps and load percentages is 93, 85, and 77% of 1RM for 3, 6, and 9 reps, respectively (3). However, in power lifts, maximal power is reached at intermediate velocities and with moderate loads (3). In the Olympic lifts, quality of performance is influenced by the level of technique (21). Because of the greater volumes used in this study, it was important to incorporate suitable load percentages to ensure little technical breakdown. Therefore, a more practical approach was taken in determining the load-rep component of volume. The participants were evaluated for their 3RM, and it was used as a base load for LV. Based on performance in LV, load for MV was set at 80–85% of LV, and load for HV was set at 70–75% of LV. These percentages were calculated using the estimated association between load and reps (3). The range of 5% was used to match the load with participant's technical breakdown limits in HV explosive exercises and to ensure optimal load for the prescribed volume pattern. Performance in LV was evaluated on the basis of ability to maintain proper technique, as described in the guidelines of the NSCA (2), and subjective symptoms of excess fatigue such as heavy breathing and muscle discomfort. To ensure uniformity, the rest period between each set for all volume patterns was maintained at 2 minutes. The participants were evaluated for Olympic lifting technical proficiency by the first author (A CSCS certified individual with experience in NCAA Division I Strength and Conditioning facilities, currently working as a Strength and Conditioning Coach with The National Cricket Academy of India) as per NSCA Guidelines (2) before commencement of the study.
Each session began with 5 minutes of passive rest followed by the measurement of resting blood lactate. The participants then completed a standardized 5-minute warm up consisting of dynamic stretching, and dynamic mobility work (e.g., body weight squats, broom stick good mornings, broom stick overhead squats, broom stick lunges). The participants then performed the prescribed three sets of power cleans. Blood lactate concentrations were again measured immediately on completion of the last set of power cleans assigned. The participants then cooled down with static stretching. No adverse events occurred. Blood lactate (millimoles per liter) was analyzed from a finger stick using a digital lactate analyzer (Lactate Plus, Nova Biomedical, Waltham, MA, USA) per the manufacturer's instructions. The relative lactate increase (percentage) was also calculated to account for individual variability in resting blood lactate values (Relative increase = [postactivity lactate − preactivity lactate/preactivity lactate] × 100). Figure 1 shows individual lactate response (percentage).
Statistical analyses were performed with SPSS version 17.0 (SPSS Inc., Chicago, IL, USA). To test the hypothesis that the greater volume of power cleans will generate greater lactate production, repeated measure ANOVA was used. The independent variable was volume pattern (3 levels depending on number of repetitions), and the dependent variable was lactate concentrations. Significance level was set at 0.05. A Pearson correlation analysis was run between weight lifted by the participants and relative increase in blood lactate to understand the relationship between volume and lactate production. In addition, multiple regression analysis was conducted to examine the individual impact of load, reps, and sets as volume on lactate production.
Table 1 shows mean load and volume lifted in all volume patterns. Figure 2 shows mean preactivity and postactivity lactate for all volume patterns.
As expected, (a) blood lactate increased from pre to post in all cases for all volume patterns and (b) as volume increased, postactivity lactate and relative lactate change increased, with F(2, 7) = 5.64, p = 0.045 from the repeated measures.
Correlations between weight lifted and relative blood lactate increase for LV and MV volume patterns were small and nonsignificant (r = 0.1 and r = 0.34, p > 0.05, respectively). However, the correlation between relative blood lactate increase and HV volume pattern was moderate and significant (r = 0.55, N = 10, p < 0.05).
Multiple regression analysis results demonstrated a greater slope associated with reps (Standardized β = 0.65) as compared with load (Standardized β = 0.20). Changes in the combination of load and reps significantly and positively influenced the lactate production (p < 0.05); this confirms that the increase in volume, as calculated from both load and reps, positively influenced lactate production (set was considered as a constant variable as the number of sets remains constant in all volume patterns).
The purpose of this study was to evaluate the effects of different volume patterns of the power clean exercise on lactate production. It was hypothesized that higher volume of power clean exercise would generate greater lactate production. Our results supported this hypothesis in that (a) different volume patterns resulted in different concentrations of lactate and (b) there was a positive correlation between volume and lactate production.
Although others have shown that lactate production is directly related to percentage of 1RM lifted (30,33), our findings are in agreement with Abernathy and Wehr (1), Gupta and Goswami (19), and Rozenek et al. (35) who reported that lactate production in resistance training is determined by volume, not load (1,19,35). The volume in this study was measured as load × sets × reps and was observed to be the most influential variable impacting lactate production. Thus, the dependence on volume observed in this study is in agreement with what was observed in previous studies.
Specifically, the volume pattern with the highest number of reps but smallest load yielded the greatest lactate production. Abernethy and Wehr (1) observed a blood lactate increase 3 times higher in 3 sets of 15RM leg press exercise (volume = 3,210 kg) compared with a 5RM protocol (volume = 1,275 kg) (1). Gupta and Goswami also observed significantly greater lactate concentration (14 mmol·L−1) in response to 6 reps of the clean and jerk at 50% of 1RM, as opposed to 3 reps at 80% of 1RM (9.3 mmol·L−1) (19). Finally, Rozenek et al. (35) observed that when holding the number of reps constant in bench press exercise, there is a positive association between elevated lactate concentration and higher volume (35).
Compared with previous studies that used more conventional resistance training exercises (e.g., the bench press and leg press [1,35]), the lactate production measured in this study was greater. This is likely because subjects in this study used more muscles, activated more type II fibers, and had larger muscle groups performing more reps at the same relative intensity compared with those using more traditional exercises; however, the response patterns of increased lactate production with increasing volume were similar (1,35).
The length of the rest interval can determine one's performance in subsequent sets, thereby affecting the volume. In addition, rest interval can also effect the total time spent to complete the performance. Therefore, the length of the rest interval may play a vital role in determining blood lactate concentrations (31). Willardson and Burkett reported that higher volume resistance exercise is typically associated with longer rest periods (39). Thus, similar rest periods for higher volume would lead to a greater physiological stress than encountered in the same activities with lower volume. Hence, the uniform rest interval of 2 minutes for all volume patterns in this study may have resulted in reduced availability of oxygen and recovery at the onset of the second and third set; this in turn, may have contributed to a greater lactate production at higher volumes.
The longer duration of higher volume activities may have also contributed to the greater lactate production. Previous studies have reported that peak lactate concentrations are achieved at 2–3 minutes after the completion of short burst activity because of the delay in lactate diffusion (20,37). Volume patterns and rest intervals of this study facilitated sufficient time for lactate diffusion, but little time for lactate clearance. Therefore, it is expected that longer durations of explosive activity would result in elevated lactate concentration. This provides evidence that HV explosive training may help in improving athlete's ability to improve lactate tolerance, and an ability to continually produce power in a metabolically fatigued state.
In this study, the greatest lactate concentrations were reported in individuals who performed larger volumes of power cleans (r = 0.55 in HV) with accurate technique. Previous investigators have reported that maximum strength and power are positively correlated with muscle endurance performance (r = 0.71) and resistance training performance (r = 0.64) (28). This may indicate that better trained individuals tend to apply better technique, lift greater volumes, and generate greater lactate concentrations. Therefore, HV explosive power training may be worth considering as supplementary training methodology for highly trained athletes.
The use of Olympic lifts as a training protocol typically involves greater loads and fewer reps to elicit optimum neural adaptation. However, results from this study may indicate that Olympic lifts protocols can be viewed in a new light, as a method to generate greater lactate concentrations by using moderate loads and higher number of reps and to improve power production abilities in a metabolically and neurologically fatigued state. In addition, subject to further studies, these protocols can be supplemented by active rest periods to enhance lactate clearance, without the risk of undesired physiological adaptations that are associated with intense aerobic work.
Although this study is novel, it is not without limitations. First, the sample size was small and it included only college-aged recreational male athletes. Future studies should use larger and more diverse samples (including younger and older athletes, women, and more competitive athletes). Additionally, these results were found only with the power clean exercise. Future research should examine the impact of other Olympic lifts and other explosive training tools to determine the optimal level of lactate concentration and clearance desired for enhanced performance in intermittent sports. Specifically, tool such as kettle bells, which are conventionally being used as an intervention to improve power endurance, and which is less susceptible to technical breakdown, can be considered. As mentioned before, future research should also examine the effects of the combination of HV Olympic lifts and active rest on lactate clearance mechanism. Finally, a word of caution is warranted regarding technique when performing multiple reps of power cleans. Because fewer (3–6) reps are the norm for this type of exercise, extreme caution and reduced weight percentages should be used when performing additional reps and sets to ensure that injury and poor form does not occur. Further investigation of the biomechanical implications of HV Olympic lifts would be beneficial.
The purpose of this study was to evaluate the effects of HV explosive power training on lactate production, with a view to modify training interventions to improve lactate tolerance, and overload the lactate clearance mechanism. As discussed before, athletes of intermittent sports have to produce power in a metabolically and neurologically fatigued state, hence, current sequencing of explosive power exercises on a typical weight training session (i.e., at the beginning of the session) with fresh neural and metabolic pathways may not be conducive enough to address requirements of such sports. However, the importance of having fresh neural pathways while performing explosive power exercises to attain maximum neural adaptations cannot be overlooked. Therefore, it is important to find training interventions that develop a variety of power production capabilities and challenge metabolic pathways.
This study indicates that strength and conditioning coaches may wish to add higher volume Olympic lift protocols in their training regimes to address aforementioned training goal. Specifically, it appears as if higher volume (e.g., 3 sets of 9 repetitions) combined with moderate loads is a good mechanism for facilitating high blood lactate concentrations and if combined with active rest, can possibly increase the capacity for lactate clearance, which could result in improved performance in sports demanding repeated anaerobic intervals. Combining HV Olympic lifting with other means of training (e.g., core strengthening exercises, mobility exercises, and other volume patterns of Olympic lifts and plyometrics) could help athletes maintain anaerobic capacity, muscle mass and power while continuing to improve in areas previously not explored.
The authors wish to thank the Department of Kinesiology of Boise State University for their administrative support. They also wish to thank Simplot Center for Athletic Excellence at Boise State University and Boise State University Strength and Conditioning team for their valuable input and participation and Boise State University Student Recreation Center for their infrastructural support. Last but not least, they would like to thank Mr. Mike Conroy for his valuable input and suggestions.
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Keywords:© 2013 National Strength and Conditioning Association
Power cleans; Lactate concentrations; Olympic lifts; Anaerobic endurance; Explosive power training