COMPARISON BETWEEN BENCH PRESS AND LEG PRESS FOR CHANGES IN SERUM CREATINE KINASE ACTIVITY AND MUSCLE SORENESS

Transcription

1 Journal of Musculoskeletal Research, Vol. 18, No. 3 (2015) (9 pages) World Scientific Publishing Company DOI: /S COMPARISON BETWEEN BENCH PRESS AND LEG PRESS FOR CHANGES IN SERUM CREATINE KINASE ACTIVITY AND MUSCLE SORENESS Alexander Joseph Koch,, Marco Machado and Jerry L. Mayhew Health and Exercise Sciences, Lenoir-Rhyne University LR Box 7356, Hickory, NC 28603, USA Exercise Physiology Laboratory, Truman State University Kirksville, MO, USA Laboratory of Physiology and Biokinetics UNIG Campus V at Itaperuna Brazil Laboratory of Human Movements Studies ISEMI-FUNITA, Itaperuna, Brazil alex.koch@lr.edu Received 14 January 2015 Accepted 24 August 2015 Published 28 October 2015 ABSTRACT We compared perceived muscle soreness (MS) and serum creatine kinase (CK) activity after upper body or lower body resistance exercise. A total of 64 previously sedentary men were randomized into two groups: bench press (BP; n ¼ 32, age ¼ 22:6 4:6 y, body mass ¼ 74:8 11:5 kg,) or leg press (LP; n ¼ 32, age ¼ 22:7 4:8 y, body mass ¼ 72:9 7:6 kg). Subjects were tested for 1RM for their respective exercise. Two weeks later, Two weeks later, subjects performed four sets to failure of each exercise at 85% 1RM. MS and serum CK activity were assessed before exercise and 24, 48, and 72 h after exercise. Volume load lifted was significantly greater during LP than BP (2428:2 356:5 kg versus 1146:9 281:7 kg, respectively; p < 0:001). Despite a lesser volume load, BP elicited greater MS ( p < 0:001) and peak CK activity ( p < 0:001) than LP after exercise at each time period. MS was modestly correlated to volume load lifted during LP (r ¼ 0:35, p ¼ 0:05) but not during BP ( p > 0:05). CK activity was not correlated with volume load for either BP or LP. In addition, MS was not Correspondence to: Alexander Joseph Koch, Health and Exercise Sciences, Lenoir-Rhyne University, LR Box 7356, Hickory, NC 28603, USA

2 A. J. Koch, M. Machado & J. L. Mayhew significantly correlated with CK at any time period. These data indicate that upper body resistance exercise elicits greater levels of MS and CK than does lower body exercise in untrained men and suggests that both factors appear to be more dependent on the muscle group engaged rather than the amount of weight lifted. Keywords: Muscle damage; Resistance exercise; Enzymes. INTRODUCTION Resistance exercise (mainly in the form of eccentric actions) may result in damage to muscle tissue. Damage can be specific to just a few myofilaments or result in large tears in the sarcolemma, basal lamina, and supportive connective tissue, thus inducing injury to contractile elements and the cytoskeleton. 6 Usually the damage is accompanied by release of creatine kinase (CK), myoglobin and other proteins into the blood 2,21 and the emergence of delayed onset muscle soreness (DOMS). The release of proteins from muscle into circulation is accompanied by an inflammatory response leading to the formation of prostaglandins and leukotrienes. Prostaglandin (specifically Prostaglandin E 2 Þ formation results in increased pain via the sensitization of Types III and IV pain afferents to chemical stimuli. Leukotrienes cause increased vascular permeability and consequently, a greater migration of neutrophils to the site of damage. Neutrophils oxidative burst can cause further damage to cell membranes. Thus, the inflammatory response results in the accumulation of fluid in the interstitial space which causes pain and swelling. 7 CK has been identified as one of the best indirect indicators of muscle damage due to its ease of identification and relatively low cost. 2 CK has been used as an indicator of training intensity and in the diagnosis of overtraining. 2,15,21 However, some issues need further discussion. There is great inter-individual variability in serum CK activity, which complicates the assignment of reliable reference values for athletes. 3,15,21 Furthermore, in the training level, 27 muscle groups involved, 26 and gender 10 can influence the results found. Studies have shown that exercises performed with the upper body cause higher levels of serum CK and muscle soreness (MS) than exercises performed with the lower body. 4,13,26 Because of the different architectures of arm and leg muscles, 16 it is probable that mechanical stress per muscle unit differs between these two muscle groups when doing exercises of the same intensity. This can be one of the reasons for different muscle damage responses. In addition, Jamurtas et al. 13 proposed that submaximal eccentric actions of lower body muscles are routinely performed during daily activities, such as downhill walking and descending stairs. It is well documented that following repeated bouts of eccentric exercise the muscles adapt themselves to protect against further damage, 6,25 lending support to the proposition of other investigators. 13,26 However, most previous studies contrasting upper and lower body exercise were performed with eccentric-only, isokinetic exercise at intensities and volumes that are not used in everyday life. 4,13,26 Machado et al. recently 19 observed higher CK activity following upper and lower body exercises that are more commonly performed: four sets of 10RM iso-inertial bench press (upper body) versus leg press (lower body) exercise in novice trainees, but they did not measure MS. Therefore, the aim of this study was to compare both the serum CK activity and

3 Comparison between Bench Press and Leg Press for Changes in Serum CK Activity and MS perceived soreness (MS) after bench press and leg press exercises performed with a relative intensity of 85% 1RM. It was hypothesized that both serum CK and MS would be greater after performing bench press than leg press. METHODS Participants The study participants consisted of 64 healthy sedentary men between 18 and 35 years old. Participants indicated that they were not currently using medical drugs, dietary supplements, or anabolic steroids, and were without joint, muscular or cardiovascular diseases. More specifically, none had a recent history (within last 3 years) of muscle or joint injuries, and all participants were apparently healthy. The participants were tested in three separate cohorts (8 12 participants at a time) at different times for almost one year. All participants reported having previous experience with weight training but none had practiced this activity for the 6 months prior to the experiment. All participants claimed to be familiar with the bench press and leg press exercises prior to the experiment. None of the participants were competitive athletes and most were university students. The experimental conditions were conducted in accordance with the norms of the Brazilian National Health Council, under Resolution No. 196, and the methods were approved by the local ethics committee. Each subject provided an informed consent document prior to participation. Participants were divided according to a computer generated randomization process into a bench press (BP; n ¼ 32) or leg press (LP; n ¼ 32) group. Comparisons of both protocol groups prior to strength testing revealed no significant difference in age, height, and body weight. Descriptive characteristics of the participants are displayed on Table 1. Table 1 Variable Descriptive Characteristics of the Subjects. Bench Press Group (n = 32) Experimental Protocol Leg Press Group (n = 32) Age (years) 22:6 4:6 22:7 4:8 Body mass (Kg) 74:8 11:5 72:9 7:6 Height (cm) BMI (kg/m 2 ) 24:0 2:9 23:8 2:0 1RM (kg) 54:0 8:6 121:4 15:6 Prior to the experimental exercise sessions, participants were tested on two separate days to determine a 1 repetition maximum (i.e. 1RM) for the bench press or leg press according to previous randomized distribution. To minimize possible errors in the 1RM assessments, the following strategies were employed: (a) all participants received standard instructions on exercise technique, (b) exercise technique was monitored and corrected as needed, (c) body position was held constant (i.e. hand width during BP and foot position during the LP test), and (d) all participants received verbal encouragement. Reliabilities for BP (ICC ¼ 0:89) and LP (ICC ¼ 0:98) have previously been shown to be excellent. 22 Two weeks following the 1RM assessments, resistance exercise sessions were performed for each specific group. All tests were performed in the morning (from 0800 to 1100 h). Participants were permitted to consume water ad libitum, and there were no nutritional recommendations provided after the exercise session. Exercises were performed for four sets of maximum repetitions to concentric failure with 85% of 1RM, with a 2-min rest interval between sets. The repetition cadence was controlled with a digital sound signal (Beat Test & Training, CEFISE, Nova Odessa, Brazil) that was adjusted so that each repetition was completed in approximately 4 s (2 s concentric and 2 s eccentric). A researcher observed all exercises performed,

4 A. J. Koch, M. Machado & J. L. Mayhew and failure was defined as the inability of participants to maintain the cadence or to complete the concentric portion of a lift. Participants provided blood samples in a seated position from the antecubital vein into plain evacuated tubes after 8 h overnight fast prior to each exercise bout, and at 24, 48, and 72 h following exercise. Samples were allowed to clot for 30 min, and then centrifuged at 1600g for 10 min. The serum was removed, and the serum CK activity was analyzed with an enzymatic method at 37 C (CK-UV NAC-optimized; Biodiagnostica, Pinhais, Brazil) in a Cobas Mira Plus analyzer (Roche, Basel, Switzerland). The CK analyses were made in triplicate and demonstrated high reliability (ICC ¼ 0.98). The MS data were assessed using a visual analog scale (VAS) of a 100-mm continuous line representing not sore at all at one end (0 mm) and very, very sore at the other (100 mm). Participants were asked to report the soreness level on the VAS while an investigator palpated the triceps brachii or rectus femoris depending on the exercise performed. Specifically, participants muscles were palpated at three sites: mid-belly of the muscle, 3-cm above and below the mid-belly), and scores were recorded. The highest score of the three sites was used for further analysis. peak difference (PD), meaning the highest postexercise (among 24, 48, or 72 h) value minus resting value, was calculated for both MS and CK. An alpha level of p < 0:05 was used to determine the significance of comparisons. Statistical analysis was completed using SPSS 17.0 for Windows (LEAD Technologies). RESULTS Exercise Volume Kolmogorov Smirnov tests revealed a normal data distribution for all variables tested ( p > 0:10 for all variables). The total number of repetitions performed for each exercise was similar (BP ¼ 24 2 reps, LP ¼ 24 4 reps, p ¼ 0:25) for an approximate total load duration of 96 s 12 s for BP and 96 s 16 s for LP. However, given the greater amount of weight lifted (LP ¼ 105:8 13:4 kg, BP ¼ 47:4 7:1 kg), LP participants lifted a greater total volume load (2428:2 356:5 kg; p < 0:001) than those performing BP ð1146:9 281:7 kg). Figure 1 displays the volume load completed during BP and LP. Creatine Kinase Repeated measures ANOVA revealed significant increases in CK after both exercises (time effect Statistical Analyses All data were analyzed for normality using a Kolmogorov Smirnov test. Soreness rating and CK activity were compared between exercises using a treatment by time (2 4) repeated measures Analysis of Variance (ANOVA). Statistical power () was calculated for both tests. In the event of significant main effects or interactions, post hoc comparisons were accomplished with Tukey s HSD test. Pearson correlations were used to assess the relationships among exercise volume, MS, and CK. For these correlations, a Fig. 1 Volume load (reps kg) lifted during four sets of Bench Press (n ¼ 32) or Leg Press (n ¼ 32) exercise

5 Comparison between Bench Press and Leg Press for Changes in Serum CK Activity and MS Fig. 2 Creatine Kinase (CK) activity in response to Bench Press (n ¼ 32) or Leg Press exercise (n ¼ 32). Different superscripts indicate significant ( p < 0:05) differences between means. F(3,60) ¼ 77.7, p < 0:001) with a significant difference among the CK levels over time between LP and BP (treatment x time effect F(3,60) ¼ 10:7, p < 0:001, ¼ 0:99). PD CK activity was significantly (t(34.5) ¼ 5:02, p < 0:001) greater after BP (615:7 341:4U L 1 Þ than after LP (303:8 83:1 U L 1 Þ, reaching its highest point at 72 h following exercise, while CK activity for LP reached its highest level at 48 h post-exercise. Figure 2 displays the CK levels following BP and LP sessions. Fig. 3 Perceived rating of muscle soreness (MS) after Bench Press (n ¼ 32) or Leg press (n ¼ 32) exercise. Different superscripts indicate significant ( p < 0:05) differences between means. Fig. 3). The perception of MS peaked at 48 h following both exercises, but by 72 h, MS was decreasing for LP while remaining at high levels for BP. For the BP exercise, no significant correlations (p > 0:05) were noted among volume load, PD CK activity, and PD MS (r ¼ 0:13 0:12). For the LP exercise, a weak correlation (r ¼ 0:39, p ¼ 0:03) was found between volume load and PD MS; no other significant correlations were noted for LP. Muscle Soreness Rating Before the exercise bout, all participants indicated a zero rating for their perception of MS. Repeated measures ANOVA found MS ratings significantly increased after exercise (time effect F(3,60) ¼ 2466:6, p < 0:001), and the pattern of change differed over time between LP and BP (treatment x time interaction F(3,60) ¼ 69:0, p < 0:001, ¼ 0:99). Again, the PD MS was significantly (t(62) ¼ 7:72, p < 0:001) greater in BP (63:9 5:9 mm) than in LP (51:1 7:3 mm; DISCUSSION Based on these data, upper body exercise (BP) elicits both greater MS and CK in the days following an exercise bout of equal intensity than does lower body exercise (LP). Our findings support previous studies that have shown that upper body exercise produces higher levels of serum CK in the blood than lower body exercises. 4,13,26 The iso-inertial exercises, consisting of both concentric and eccentric muscle actions, performed by participants in the present study

6 A. J. Koch, M. Machado & J. L. Mayhew produced similar results to the isokinetic, eccentric-only exercises performed in the prior experiments, 4,13,26 and similar to the other published observations of iso-inertial exercise by Machado et al. 19 The rise in serum CK activity after exercise results from CK enzymes originating in the muscle fibers and leaking through perforations in the damaged cell membrane. The time course of CK activity differed between exercises, with CK activity peaking 48 h after LP versus at 72 h after BP. Previous comparisons of CK activity after upper body versus lower body exercise have consistently found a similar pattern: where CK activity achieved a later peak of greater magnitude after upper body versus lower body exercise. 4,13,26 All previous studies employed eccentric-only, isokinetic movements. This likely contributed to the notable difference observed in the magnitude of increase in CK activity after the BP in the present study, as compared to the isokinetic, eccentric-only actions of the previous studies. In the present study, PD values for CK activity after LP ( U L 1 Þ were similar to the mean values observed after isokinetic, eccentric actions of knee extensors. 4,13,26 However, CK activity after BP ( U L 1 Þ was substantially (two to five times) lower than the values reported following isokinetic action of the elbow flexors 4,13,26 or extensors. 4 This is not unexpected as CK activity following iso-inertial movements is typically lower than that reported after eccentric-only, isokinetic actions. 5 The consistent finding among all comparisons of CK activity after upper versus lower-body resistance exercise appears to be that upper-body exercise produces greater magnitude increase in CK activity that persists for a longer period of time after the exercise. Jamurtas et al. 13 proposed that submaximal eccentric actions during daily activities, like downhill walking and walking down stairs, are routinely encountered by lower body muscles. Thus, lower body muscles would likely produce a lesser rise in soreness and CK after resistance exercise than would upper body muscles. The repeated bout effect, where muscles adapt to a single bout of damaging exercise to protect against further damage from a subsequent bout, is well documented to occur. This adaptation appears to include a change in the pattern of motor-unit recruitment, a blunted immune response, the generation of more sarcomeres in series, and reduction in stress-susceptible fibers. 6 The sedentary participants in the present study were likely less familiar with upper-body eccentric actions that the BP bout presented. Thus, the relatively greater novelty of BP might explain the greater delta CK and soreness ratings observed following BP in the present study. However, this explanation may not be entirely satisfactory. Even well-trained individuals display MS and elevations in CK after performing a new exercise. 11,27 Indeed, in some cases, trained individuals have displayed greater MS after exercise than those who were untrained. 27 Differences in muscle fiber type between the upper- and lower-body muscles may also contribute to the differences in soreness and CK levels that we observed. Specifically, type II muscle fibers appear to be more susceptible to muscle damage than type I fibers. 11 While participants in the present study were not measured for muscle fiber type, previous experiments have generally found a higher proportion of type II fibers in muscles involved in BP, such as the triceps brachii, than in muscles recruited during LP, such as the vastus lateralis. 24 The extent of muscle damage may also be affected by the degree to which a muscle is stretched. Saka et al. 26 found greater MS and CK in participants after performing eccentric elbow flexion versus those performing eccentric knee extension. They explained their findings as likely

7 Comparison between Bench Press and Leg Press for Changes in Serum CK Activity and MS due to the greater eccentric load per unit muscle volume experienced during exercise of the elbow flexors compared to exercise of the knee extensors. Their experiment consisted of performing eccentric exercise on an isokinetic machine, and the total work their participants performed was corrected for muscle volume involved. Following that correction, they reported that elbow flexors performed more than three times the amount of relative work (joules/cm 3 Þ than knee extensors. 26 In the present study, total volume load lifted was significantly greater during LP than BP. Unfortunately, in our participants, muscle volume could not be easily quantified, given the multi-joint nature of the exercises involved. However, total work (uncorrected for muscle volume) performed by Saka et al. s participants was also greater for the lower body exercise. 26 Had we been able to measure muscle volume in the present study, it is possible that our results would have shown a similar pattern. Another variable that may account for differences in soreness and CK between BP and LP is the difference in vasculature between the upper and lower body. Specifically, upper body blood vessels appear to be more distensible than lower body blood vessels. 9 This distensibility has been linked to greater perception of pain in the presence of an applied pressure. 1,8,9,28 Thus, the greater perception of pain following BP may be related to a greater vascular distention of the arms in response to local edema. Increases in small arterial elasticity following heavy exercise have also not been related to elevations in CK. 14 The extent of MS and the magnitude of rise in CK after either exercise were not significantly related to one another. This supports previous findings that the perception of soreness is a poor indicator of the magnitude of muscle damage. 23 The lack of a relationship between volume load lifted and either PD CK activity or MS following BP was somewhat surprising. This is curious, especially when contrasted with LP, where there was a weak correlation between volume load and delta soreness. Some previous investigations have concluded that the volume load lifted is a major determinant of CK levels in blood. 18,20 However, others have reported no relationship between total work performed or the amount of muscle mass recruited and the magnitude of increase in plasma CK after exercise. 22 In the present study, we found that a greater volume load during LP was mildly related to greater perception of soreness and that total repetitions performed in both exercises were weakly related to the increase in CK. Taken together, these results suggest that mechanisms behind post-exercise MS and CK levels are complex, and that the volume of exercise performed plays only a minor role in the development of post-exercise MS or elevations of CK. Other variables, in addition to the volume of work completed, affect the extent of muscle damage. For example, several previous studies have found that CK elevation after resistance exercise is affected by rest interval duration 17,20 as well as the volume of exercise performed. The extent of rise in CK is highly variable, and genetic variations lead some individuals to be classified as either high responders (HR) or normal responders (NR). 12 Individuals categorized as HR display abnormally large elevations in CK after eccentric exercise compared to NR. Genetic variation, specifically possession of CK-MM NcoI AA genotype 12 and the ACE II genotype, 29 or a higher percent body fat 12 have been found to be related to HR. It is possible that our results could be an artifact of having a greater number of HR participants in the BP group. However, when our results are combined with the previous studies. 4,13,26 that have compared upper and lower body exercise, the consistent findings of greater soreness and CK following upper body exercise suggest true differences in the exercise response between muscle groups rather than an artifact

8 A. J. Koch, M. Machado & J. L. Mayhew of subject selection. Most notably, Chen et al. s recent experiment employed the same participants exercising different (elbow versus knee, extensor versus flexor) muscle groups repeatedly. 4 Interestingly, they observed that elevated CK responses occurred after exercise of some muscle groups, but not others, within the same subject. Thus, there is evidence to support that the muscle group exercised may be the most important factor in determining CK response. Chen et al. 4 noted differences in markers in muscle damage not only between upper body and lower body muscles, but also in antagonist muscle groups (knee extensor versus flexor) around the same joint. From these differences, they concluded that different characteristics of muscle damage between muscles are very specific, and suggested it is ideal to use specific exercise models of specific muscles to understand the nature of muscle damage for a given muscle group. In contrast, Machado et al. 19 found HR tended to be the same individuals, regardless of whether they were exercising upper or lower body muscles, and thus suggested that genetic or systemic factors may provide the best explanation for individual variation in CK activity after exercise. Machado et al., 19 similar to the present study, stimulated a rise in CK activity using multi-joint, large muscle mass exercises for the upper and lower body. While the nature of compound movements makes identifying the specific locus that gives rise to differences between muscle groups more difficult, the work of Machado et al. 19 and the present design present the advantage of replicating an exercise mode, intensity and cadence that are used in many strength training settings. While MS and CK activity were assessed following the exercise bout in the present study, the fact that no measures of muscle function were assessed in our participants after the exercise bouts is a limitation of the present study. In summary, upper body resistance exercise evokes greater rises in CK activity and the perception of MS than does lower body resistance exercise performed at the same relative intensity. There are several possible reasons for this difference, including differences in muscle architecture, fiber type, vasculature, and habitual activation that exist between upper and lower body muscles. The extent of MS and magnitude of rise in CK after exercise appear to be unrelated to one another, a phenomenon which requires further investigation. MS is mildly related to the amount of exercise that is performed during LP, but has no relationship to the volume load accumulated during BP. At present, the precise determinants of the magnitude of rise in CK and MS after resistance exercise remain elusive. We represent that this submission is original work and is not under consideration with any other journal. References 1. Arndt JO, Klement W. Pain evoked by polymodal stimulation of hand veins in humans. J Physiol 440: , Brancaccio P et al. Serum enzyme monitoring in sports medicine. Clin Sports Med 27(1): 1 18, Chen TC. Variability in muscle damage after eccentric exercise and the repeated bout effect. Res Q Exerc Sport 77(3): , Chen TC et al. Comparison in eccentric exercise-induced muscle damage among four limb muscles. Eur J Appl Physiol 111(2): , Clarkson PM. Exercise-induced muscle damage animal and human models. Med Sci Sports Exerc 24(5): , Clarkson PM, Hubal MJ. Exercise-induced muscle damage in humans. Am J Phys Med Rehabil 81(11 Suppl): S52 S69, Connolly DA, Sayers SP, McHugh MP. Treatment and prevention of delayed onset muscle soreness. J Strength Cond Res 17(1): , Davenport PW, Thompson FJ. Mechanosensitive afferents of femoral-saphenous vein. Am J Physiol 252(2 Pt 2): R367 R370,

9 Comparison between Bench Press and Leg Press for Changes in Serum CK Activity and MS 9. Eiken O, Kolegard R. Comparison of vascular distensibility in the upper and lower extremity. Acta Physiol Scand 181(3): , Fredsted A, Clausen T, Overgaard K. Effects of step exercise on muscle damage and muscle Ca 2þ content in men and women. J Strength Cond Res 22(4): , Friden J, Lieber RL. Eccentric exercise-induced injuries to contractile and cytoskeletal muscle fibre components. Acta Physiol Scand 171(3): , Heled Y et al. CK-MM and ACE genotypes and physiological prediction of the creatine kinase response to exercise. J Appl Physiol 103(2): , Jamurtas AZ et al. Comparison between leg and arm eccentric exercises of the same relative intensity on indices of muscle damage. Eur J Appl Physiol 95(2 3): , Kampus P et al. Association between arterial elasticity, C-reactive protein and maximal oxygen consumption in well-trained cadets during three days extreme physical load: A pilot study. Physiol Meas 29(4): , Lazarim FL et al. The upper values of plasma creatine kinase of professional soccer players during the Brazilian National Championship. J Sci Med Sport 12(1): 85 90, Lieber RL, Friden J. Functional and clinical significance of skeletal muscle architecture. Muscle Nerve 23(11): , Machado M, Willardson JM. Short recovery augments magnitude of muscle damage in high responders. Med Sci Sports Exerc 42(7): , Machado M et al. Effect of varying rest intervals between sets of assistance exercises on creatine kinase and lactate dehydrogenase responses. J Strength Cond Res 25(5): , Machado M et al. Is exercise-induced muscle damage susceptibility body segment dependent? Evidence for whole body susceptibility. J Musculoskelet Neuronal Interact 13(1): , Mayhew DL, Thyfault JP, Koch AJ. Rest-interval length affects leukocyte levels during heavy resistance exercise. J Strength Cond Res 19(1): 16 22, Mougios V. Reference intervals for serum creatine kinase in athletes. Br J Sports Med 41(10): , Nosaka K, Clarkson PM, Relationship between postexercise plasma CK elevation and muscle mass involved in the exercise. Int J Sports Med 13(6): , Nosaka K, Newton M, Sacco P. Delayed-onset muscle soreness does not reflect the magnitude of eccentric exercise-induced muscle damage. Scand J Med Sci Sports 12(6): , Plomgaard P et al. The mrna expression profile of metabolic genes relative to MHC isoform pattern in human skeletal muscles. J Appl Physiol 101(3): , Proske U, Allen TJ. Damage to skeletal muscle from eccentric exercise. Exerc Sport Sci Rev 33(2): , Saka T et al., Differences in the magnitude of muscle damage between elbow flexors and knee extensors eccentric exercises. J Sports Sci Med 8: , Vincent HK, Vincent KR. The effect of training status on the serum creatine kinase response, soreness and muscle function following resistance exercise. Int J Sports Med 18(6): , Wooley CF, Sparks EH, Boudoulas H. Aortic pain. Prog Cardiovasc Dis 40(6): , Yamin C et al. ACE ID genotype affects blood creatine kinase response to eccentric exercise. J Appl Physiol 103(6): ,