There have been continued efforts to find more effective training techniques and to investigate the science of muscular adaptations and recovery (6). With advances in both technology and an understanding of training methods, insights into the balance between performance and recovery time have become better understood. Because performance on the field in competitive situations is what is most scrutinized by all stakeholders, this isolated period of time receives the most attention. For baseball pitchers, this means being able to perform at optimal levels consistently. An example of the implications of a rest period being important is the advent of management sticking more than ever before to a 100-pitch count. Ironically, despite the introduction of the 100-pitch count and the increased use of relief pitchers, the injury rate of pitchers continues to increase (10). If the decrease in the number of pitches is not improving pitching, then can recovery between innings improve pitching?
As pitchers continue to do repetitive high-intensity motions, blood lactic acid (BLa) levels will increase in the involved muscles and general circulation. The accumulation of BLa increases hydrogen ions (H+) and causes a decrease in the pH within the muscle; low pH mediated by increased BLa levels can impair motor control during pitching (3,11,15). This is because of several factors including the following: decreased blood flow and low oxygen content in the blood, and lack of aerobic recovery to flush the waste product H+ from the shoulder (1,15). This can impair motor control during the pitching process (3). Finding the most effective form of recovery is beneficial when trying to maintain or enhance a pitchers performance (18). As a pitcher becomes fatigued, there is an increased likelihood of injury; therefore, recovery is of utmost importance (5). In addition, fatigue may cause a decrease in the maximum power of muscular contraction (13). From a recovery perspective, an increase in blood flow may decrease H+, which would in turn potentially mitigate fatigue and the likelihood of subsequent injury. Moreover, an increase in blood flow may lead to improved performance (3,8).
Several strategies to facilitate recovery have been investigated in the literature, including active recovery (AR), passive recovery (PR), and electromuscular stimulation (EMS). The AR, wherein athletes participate in an active movement, often cardiovascular, in an effort to increase blood flow, has been shown in previous studies to be the most effective form of recovery (1,3). The rationale for AR is to allow vasodilatation and oxygen rich blood to increase the rate of H+ clearance in the muscle. It has been found that the best AR has come from activity at about 60% of estimated maximum heart rate and slowly declining the estimated maximum heart rate to about 30% (7,9,17).
Passive recovery is simply rest, often in the form of sitting, lying down, or stretching. Typically, 15-25 minutes of rest is thought to be the optimal time for returning pH levels to normal (1). This form of recovery has the ability to allow the body to maintain and rebuild its glycogen stores, because of its inactive method (2). Passive recover in some studies has shown to have the same effect of lowering BLa as AR but without the energy expenditure (3,12).
Electromuscular stimulation, which is a relatively new modality for postexertional recovery, has received very little attention in the literature. It is based on the principle that EMS induces local muscle contraction without corticospinal excitation, thereby increasing blood flow and reducing lactic acid build-up. Studies have shown that EMS increases blood flow more than when voluntary muscle exercises are used (8,19,20). This increase of blood flow has been shown to help reduce H+ levels associated with lactic acid build-up (19). The theoretical advantage of EMS is that focal muscle stimulation can increase blood flow without accelerating the heart frequency and without increasing arterial blood pressure (13). Thus, muscle contractions occur without cardiovascular strain or mental fatigue (4).
Presently, there is little evidence to support the use of 1 recovery method over another between innings while pitching in a baseball game. Therefore, the purpose of this study was to determine which of the 3 aforementioned recovery methods (AR, PR, and EMS) would be the most appropriate to administer during the rest periods between innings in baseball pitchers. Two primary aims and 1 secondary aim guided this study. Our primary aim was to determine which of the 3 recovery methods was best at decreasing BLa levels in the rest period between innings. A second primary aim was to determine if the BLa levels for each of the 3 recovery methods was consistent with how the pitchers perceived their recovery for each of the 3 recovery methods. A secondary aim was to determine if the intensities of the inning before administration of the recovery methods were consistent across the 3 conditions. This would be done by measuring the average pitch speed and self-reported pitching intensity.
Experimental Approach to the Problem
All participating pitchers received instruction and demonstrations on the testing procedures before the start of the study. The design of the pitching order and format was based on the typical pitching format used by most baseball teams. Pitchers were to follow the normal pitching recovery routine, as prescribed by the pitching coach, between testing days. The pitchers were placed on a 4-day pitching rotation and performed the protocol exercises, as directed by the pitching coach, on nonpitching days. Pitchers were instructed to follow the dietary and hydration protocols as instructed by their pitching coach. For the conditions to most closely approximate an actual game, pitchers were evaluated during live game play practices. Pitchers were tested at roughly the same time every testing day. There was no control of a pitcher's pitching order, the number of pitches, or the amount of time for recovery between innings. This allowed for the most accurate simulation of game play, and was done to try to prevent the pitchers from changing their normal pitching routine. Pitching was done outdoors and in the cool to cold weather typically found with preseason conditions. On assigned live pitching days, players were to follow normal warm-up procedures. Immediately after pitching, BLa was tested. The pitchers also rated their pitching performance at this time. The selected recovery method was done for 6 minutes. At the end of 6 minutes, BLa was retested, and they rated their recovery. This was repeated for 3 innings using the same form of recovery for each inning. Each pitcher was exposed to all 3 forms of recovery.
Seven college men with a mean age of 20.86 years (±1.25SD) with an average height of 180.12 cm (±7.39SD), and average mass of 84.89 kg (±10.71SD) who were NCAA Division II college baseball pitchers participated. All participants had at least 1 season of pitching at the collegiate level, before testing. Each participant had undergone and passed a preseason medical examination performed by team doctors. At no time during this study were any of the participants under any medical supervision for conditions that would not allow for the normal biomechanics of a pitch. All participants were informed of risks, expectations, rules, and regulations of participation in the study. An explanation of the procedures and purpose of the study was given. Subjects were not required to participate and were free to remove themselves from the testing at anytime. The participants read and signed a University institutional review board approved written informed consent.
Each pitcher underwent the same procedures in a repeated-measures design. Data were collected and used from the first 3 innings pitched, for each of the 3 recovery methods. That is, each pitcher was administered 1 recovery method for 3 innings on the same day. The next testing day the pitcher was administered a different form of recovery for all 3 innings. This was repeated again on the third testing day (Figure 1). To get an accurate measure of how the recoveries affected the pitchers, 3 forms of measurements were used. The difference BLa levels was used as a biological measurement, average pitching speed was the physiological measurement, and the psychological measurement was done through the use of a scale to determine how the pitchers perceived their pitching and recovery. Subjects were tested at roughly the same time everyday and were instructed to maintain hydration levels as directed by their pitching coach.
The speed of every pitch was measured using a STALKER PRO Pitching speed radar gun (STALKER Professional Sports Radar, Applied Concepts, Inc., Plano, TX, USA), and the average speed for that inning was then calculated. Immediately after the inning ended, BLa was collected using a finger prick on the nonpitching hand. The Lactate Pro Blood Lactate Analyzer (Lactate Pro LT-1710, Arkray Factory, Inc., Shiga, Japan) was used to quantify the BLa levels. The study done by Pyne et al. found that the reliability of the Lactate Pro analyzer was r = 0.99 (12). Pitchers were also asked to rate their pitching intensity from that inning using a 0-10 scale with 0 indicating that the pitcher perceived no intensity in his pitching and 10 indicating that the pitcher gave the highest possible intensity for that inning. The form of recovery (AR, PR, or EMS) for the 6-minute recovery period was started immediately after BLa was collected. After the 6-minute period, BLa was collected again and the pitcher was asked to rate their recovery using a 0-10 scale with 0 indicating a feeling of no recovery and 10 indicating a feeling of full recovery (Figure 1).
Passive recovery for this research was defined as sitting in the players' area with no activity for the 6-minute period. Pitchers were instructed to avoid any physical exertion during this 6-minute recovery period.
The form of AR for this study was jogging for the 6-minute recovery period at approximately 60% of the estimated maximum heart rate, as predicted using the Karvonen method (third edition). The pitchers were instructed to gradually decrease their jogging intensity during the period to gradually reduce the heart rate. The heart rate was to be decreased by about 15% every 2 minutes, with the final 2 minutes at approximately 30% of the pitchers estimated maximum heart rate (7,9,17).
The EMS unit that was used for this study was the Compex Sport unit (Compex Sport, Compex Technologies LLC, Ecublens, Switzerland). The participants received EMS recovery treatments using the “Active Recovery” setting, for a period of 6 minutes. The “Active Recovery” setting stimulates efferent motor neurons with a biphasic waveform. The specific setting was a rectangular biphasic symmetrical waveform, and the pulse width was 250 microseconds (1 microsecond = 10−6 seconds). The program frequency started at 9 Hz and automatically decreased every 2 minutes. The first 2 minutes were at 9 Hz, the following 2 minutes were at 8 Hz, and the last 2 minutes were at 7 Hz (13,14). Six electrical leads were placed on the biceps brachii and triceps brachii muscle bellies; anterior and posterior deltoid; and anterior and posterior portions of the upper trapezius.
A 2 (time: pre and post) × 3 (treatment: AR, PR, EMS) × 3 (inning: first, second, and third) analysis of variance (ANOVA) with repeated measures was conducted to determine differences in BLa levels between recovery conditions. An a priori alpha of 0.05 was used for significance. There was no 3-way interaction (F(4,24) = 1.634, p = 0.244, power = 23.9%). Likewise, there were no 2-way interactions for inning by time (F(2,12) = 2.051, p = 0.171, power = 34.0%) or inning by condition (F(4,24) = 0.800, p = 0.421, power = 12.6%). There was, however, a significant interaction for condition by time (F(2,12) = 19.953, p ≤ 0.0005, ηp2 = 0.769 (Figure 2). To break down this interaction, 5 simple main effects tests were conducted (i.e., 3 paired t-tests and 2 repeated measures ANOVAs) using a Bonferroni corrected alpha (α = 0.01). Paired t-tests were used to determine if there was a significant difference in BLa levels before and after each of the treatment conditions. The ANOVAs were used to determine if the groups were different at pre and postmeasurement times. There were no significant differences over time for the PR condition (p = 0.017) or the AR condition (p = 0.134). However, there was a significant reduction in the EMS condition (p ≤ 0.0005). There was a statistically significant difference between the groups before treatment (p = 0.008). Pairwise comparisons reveal that there was a significant difference between the PR condition and the EMS condition (p = 0.020). There was no significant difference between the EMS and AR conditions (p = 0.087) and between the AR and PR conditions (p = 1.00). There was no significant difference between the groups after the treatment (p = 0.022).
To determine if the perceived recovery rate of the pitchers was consistent with the lactic acid levels, a repeated-measure ANOVA was conducted. The results demonstrated that there was a statistically significant difference (F(2,12) = 6.989, p = 0.01) among the 3 conditions: PR (mean = 7.43, SD = 1.42), AR (mean = 5.71, SD = 0.78), and EMS (mean = 8.00, SD = 0.72). Perceived recovery was greater for the EMS condition compared to the AR condition (p = 0.006) but not to the PR condition (p = 212). There was no difference between the PR condition and the AR condition in perceived recovery (p = 1.00).
Because 7 pitchers participated in game play situations (i.e., no regulation of the intensity and number of pitches) before the 3 different recovery conditions on 3 different days, it would be important to determine if their pitching intensity was consistent across the conditions. To do this, 2 repeated measures ANOVAs were conducted, 1 for average pitch speed during that inning and 1 for the pitchers' subjective rating of pitching intensity of the same inning. There was a statistically significant difference in average pitch speeds in the innings before treatment for the PR condition (mean = 74.29, SD = 3.90), AR (mean = 69.95, SD = 3.78), and the EMS (mean = 75.57, SD = 2.97), F(2,12) = 54.047, p ≤ 0.0005. Pairwise comparisons revealed that the AR condition had a lower average speed compared to the other 2 conditions; ps ≤ 0.0005. There was no difference in speed between the AR and the EMS conditions; p = 0.161. The pitchers' subjective rating of their pitching intensity for the PR condition (mean = 7.05, SD = 0.59), AR (mean = 6.19, SD = 1.18), and the EMS (mean = 7.81, SD = 1.00) was significant and mirrored the pitch speeds in rank order, F(2,12) = 7.832, p = 0.007 (Figure 3). Pairwise comparisons revealed that the EMS condition had a greater pitch intensity than the AR condition, p = 0.015. The other 2 pairwise comparisons were not statistically different, ps ≥ 0.295.
Results from this study suggest that recovery, in terms of reduction of BLa levels in the time between innings for baseball pitchers, was best for the EMS condition. The EMS was the only condition that had a significant decrease in BLa levels during this recovery period. There was no change in BLa acid levels for the AR and PR conditions. In addition, perceived recovery was best for the EMS and PR conditions. There was no difference between the AR and PR conditions for perceived recovery. Taken together, these results offer preliminary evidence that EMS is better than AR and PR which are both currently the most common modalities of recovery. Interestingly, it should be noted that in the inning before the recovery conditions, the most intense innings in terms of pitching speed and subjective ratings were the EMS and PR conditions, both of which counterintuitively faired better in measurements of recovery compared to the AR condition. In light of these current findings, future research regarding recovery with EMS using more rigorous methodology is warranted.
This study found that the AR was not beneficial to a baseball pitcher's speed or their perceived effort level, which is contrary to other studies. There was a significant decrease in the mean average speed to 70.0 mph, which correlated with a BLa increase of 1.452 mmol·L−1, with the use of AR. The “tired” feeling may be explained by the decreased effective blood flow to replenish the glycogen stores (3).
With the short recovery time, PR caused the heart rate to decrease, so the lactic acid and by-products, including (H+), were not eliminated as effectively. But, the pitcher is not using the glycogen stores that are left within the muscle to recover. So, there would not be any further depletion of glycogen stores within the muscle. There may actually be a slight increase as the lactic acid and by-products are cleared. The body may physiologically adapt to become more effective in the filtration of the blood during this recovery time, partially because there would not be a workload slowing biological processes down.
These findings are actually similar to other research that tested AR vs. PR in repeated-sprint cycles. Spencer et al. compared the use of AR and PR and found that despite no differences in the majority of performance measures, AR resulted in a significantly lower final peak power, a greater peak power decrement, suggesting a potential suboptimal effect of AR during repeated-sprint exercise (16). This information also supports the fact that AR and PR are not the most effective method of recovery for pitching. The AR and PR did not significantly reduce BLa levels. This too was consistent with their self-reported perception of recovery.
The studies that have been conducted with the use of EMS as a recovery technique were done as recovery method after aerobic endurance events. This is the first known research done to determine if the use of EMS as a recovery technique during anaerobic events is an effective technique. Further studies need to be done to find out if the 6-minute recovery period is the most effective amount of time for the baseball pitcher. The psychological aspects of the use of EMS may also play a role in the improvement found with its use.
The results of this study suggest that EMS is the most effective method of reducing BLa with a 6-minute recovery period between innings when compared to AR and PR. With the use of EMS, lactic acid level decreased by an average of 2.752 mmol·L−1during the recovery period, indicating a reduction of H+ and by-products; this mirrored the pitchers' perception of recovery. For some of the pitchers, their recovery lactic acid levels were lower than their initial levels. The EMS gave a mean decrease of 2.334 mmol·L−1 over the most common method of recovery, PR. The EMS had a superior decrease in the difference of 4.204 mmol·L−1 over AR.
These results suggest that the blood is being effectively cleared of the H+ with the use of the EMS (20). This clearance would include an increase in the amount of new blood into the muscle. This new blood may include glycogen that would be able to be stored within the muscle more effectively because of the lack of the H+ that may prevent storage (15). The EMS provides the benefits of AR without the cardio strain (13). This may allow the clearance of the muscle without the use of the glycogen stores to do the contractions (13). The increase in pitching speed may be accounted for by the increase in glycogen within the muscle (20). Also, it is possible that EMS may afford “rest” to the nervous system because muscle activation is mediated by direct electrical stimulation rather than cortical-mediated activation that occur during AR methods (20).
One limitation to this study was that in an attempt to allow for free game play, the pitching count and type of pitches were not tracked. This was done to try to prevent the pitchers from changing their normal pitching routine. Future studies should consider employing a more regulated pitching protocol so that the dosing of exertion is similar in all conditions. Another limitation was that the AR condition was not long enough to receive the full benefits of AR. The heart rate remained too high for the clearing of the blood and by-products. With the increase heart rate the liver's work rate is decreased. This also would inhibit the uptake of glycogen (20). The subject's medications and supplementations were not controlled. This may have had an effect on the clearance of the H+ or uptake of glycogen. Another limitation was that the statistical power was strong enough to observer the 2-way interaction of condition by time; however, the overall design was underpowered for the 3-way interaction.
We recommend that baseball pitchers consider employing EMS between innings to decrease BLa levels and to improve self-reported recovery, both of which may potentially lead to an increase in pitching performance. If EMS is not available, PR may help to improve perceived recovery; however, it is not effective for decreasing BLa levels. Based on our findings, we cannot confidently recommend AR as a method of recovery for baseball pitchers between innings.
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