Studies yielding mixed results have shown that concurrent training can interfere with strength and endurance (1,4,8,9,19), have no effect on athletic performance (2,3,15), positively affect strength (6,10,18,20,27), negatively affect power (29), and positively affect muscular or aerobic endurance (13). To determine why these research studies have shown such a discrepancy in results, they were examined for volume of work done in the experimental and control groups. It was noted that the studies could be categorized into 2 groups: those that used equal training volume (10,19,27) and those that had a huge discrepancy in training volume between groups (2–4,11,12,18,20,22). The studies that had equivalent training volume exhibited positive (10,27) and negative performance results (19). The same was found with studies that had approximately double the volume between groups; both positive (18,20) and negative performance results (4,11,12) were found.
It was hypothesized that the high volume used may have caused overtraining in the lower performing groups, and this hypothesis is supported by findings by Hickson (12). One group trained for 40 minutes and the other for 80 minutes. During the first 8 weeks of the 10-week study, both groups improved at a fast rate, and then during weeks 9 and 10, the group that trained for 80 minutes declined sharply in performance. Hickson (12) suggested that if he had stopped the training at week 8, his results would have probably shown that concurrent training had an additive effect (better than when either type of training was performed alone). Bell et al. (2) found similar results; the first 9 weeks of his 12-week study showed steady improvement, followed by a sharp decrease in performance at week 10 in the high-volume concurrent group. He suggested that the subjects may have suffered from overtraining. In studies where volume was reduced, positive performance outcomes from training were achieved. Hakkinen et al. (10) and Kraemer et al. (18) showed that significantly reducing the overall intensity and volume of the workout resulted in improvements in strength and power. Based on these studies, it was hypothesized that the strength, endurance, and maximal-effort cycling (SEC) group (given the correct volume, intensity, and mode of exercise) would outperform the strength and endurance (SE) group.
Maximal-effort cycling was added to the experimental training group because it was hypothesized that a sharp stimulation of the anaerobic glycolytic system would produce supplementary or even synergistic performance outcomes. The research by Hickson (12) and the general adaptation syndrome (GAS) (25) supported the investigators’ proposition. Hickson (12) stated that there may be some mechanism by which the combination of training modalities produces not only positive improvement but one that is additive in nature. Additionally, the GAS theory implies that as long as recovery is sufficient and stress is not overly intense, the body will adapt and perform at a higher level. Therefore, multiple training modes that included short-term anaerobic, medium-term glycolytic, and longer-term aerobic modes were incorporated into the training program.
Energy system interplay (24) was another reason for including maximal-effort cycling tests in the SEC group. Numerous factors and different types of muscle actions at varying speeds and tensions contribute to performance in sports (6,30). Accordingly, it is logical to assume that the adenosine triphosphate phosphocreatine, glycolytic, and aerobic energy systems should all be trained to some extent, at varying volumes, durations, and intensities to maximize the overall general physiological functioning of an athlete. A shot putter, for example, might spend all training time focused on short-duration strength and power training but be incapable of performing well on an anaerobic maximal-effort cycling test or V[Combining Dot Above]O2max test. Increasing the capacity to perform well in all of these areas—to some extent—should provide a comprehensive base to more strongly support any physical activity. This reflects a degree of interplay between energy systems to achieve maximum performance and is a further basis for including maximal-effort cycling as part of the training protocol in the SEC group.
Flexible nonlinear periodization was added in both the SE and the SEC groups in hopes of minimizing the possibility of overtraining. If a subject was tired on a particular day, he or she could choose to do an easier workout as long as it was made up later in the training mesocycle. Because flexible nonlinear program design has been shown to increase strength (23), it was included as part of the SE and SEC programming. Therefore, the purpose of this investigation was to combine concurrent training, flexible nonlinear periodization, and anaerobic maximal-effort cycling testing (in a concurrent training format) to increase strength and power.
Experimental Approach to the Problem
Because many concurrent studies demonstrated signs of overtraining (1,4,8,9,19), it was hypothesized that a study that started slowly and progressed gradually over time would result in positive performance outcomes. To minimize the risk of overtraining, a flexible nonlinear periodization protocol was proposed to allow subjects to adjust training intensities themselves and recover adequately for challenging training sessions. This would therefore allow for appropriate rejuvenation between workouts. Furthermore, based on the research of Hickson (12), the GAS (25), and the interdependence of energy systems, it was hypothesized that combining 3 modes of training (weight training, treadmill running, and maximal-effort cycling) would enhance strength and power.
A pretest-posttest randomized group design was used to test the hypothesis that the SEC group would gain more strength and power than the SE group. The independent variable was an exercise group with 2 levels: endurance and strength, with or without a maximal-effort cycling. Effective randomization in group assignment was therefore critical in demonstrating a cause-effect relationship based on this.
The standing broad jump to measure lower-body power (14) and the seated chest press to measure upper-body strength (1) were used as dependent variables to determine the effect of maximal-effort cycling on anaerobic power performance and strength, respectively. The standing broad jump tests whole-body neuromuscular coordination by taxing the short-term explosive anaerobic energy system. The arms, legs, and trunk area are all used to achieve maximum jump distance. It is a simple test yet very comprehensive in the range of physiological factors engaged while executing the jump.
The chest press requires less coordination but is focused specifically on upper-body strength. These 2 tests were chosen, in part, because of their relative safety and ease of administration. More importantly, the standing broad jump was chosen because concurrent training has previously been shown to negatively affect power (29), and the investigators wanted to determine if the SEC training program could prevent this negative performance outcome. Aerobic testing was not included because of the overwhelming evidence that it enhances V[Combining Dot Above]O2max (2,3,10–12,18–20,27,29). The chest press was used because it evaluated strength, which has been shown to be negatively affected in a concurrent training program (3,11,12,19). The investigators wanted to see if the correct training combination could prevent this negative performance outcome.
Subjects in this study were from a small urban college of ∼2,300 students. As mandated by the college, all students had a fitness requirement to fulfill as part of their education, and this could be fulfilled in a number of formats. Students could choose from classroom-based exercise courses, scheduled weight training courses, or a number of other activities. As such, weight training experience was not a requirement for inclusion in this study, and different levels of experience were expected.
Before the investigation, subjects were informed of the experimental risks and signed consent documents according to the institutional review board guidelines. Thirteen male and 7 female students (mean± SD: age, 22.5 ± 4.1 years; height, 173.5 ± 12.4 cm; weight, 79.4 ± 20.2 kg; strength training experience, 2.4 ±2.2 years) participated in this study. Students were randomly assigned to an SE group (n = 10) or an SEC group (n = 10). The average initial fitness level of women based on average pretest long jump performance (134 cm) was poor, and for malesmen, it was above average (196 cm) when compared with 15- and 16-year-old athletes (15). No established norms were available to compare initial upper-body fitness levels for chest press using the Cybex converging plate loaded chest press (model 5227-90; Cybex, Owatonna, MN, USA).
All screening, pretesting, training, and posttesting occurred between the hours of 10:10 and 11:05 AM on a Monday or Wednesday, or on both days, over 16 consecutive weeks of the spring semester. The first week consisted of health screenings, testing practice, and instruction on the proper use and execution of the exercise machines. All subjects were instructed to follow MyPyramid nutrition guidelines and to drink as much water as they wanted, before, during, and after exercise. Pretesting occurred during the first 2 weeks. Both groups were then assigned a training program that was 13.5 weeks in duration. Posttesting immediately followed the 13.5-week training program.
All subjects were required to fill out a revised Physical Activity Readiness Questionnaire. After subjects were evaluated and found to be healthy enough for intense exercise, instruction on proper warm-up, stretching, and pretesting exercise technique was given. Subjects were also given time to practice and become familiar with the pretests to minimize the rapid performance increase in neuromuscular coordination that can occur during the early phases of training (16).
Before testing, a 10-minute general warm-up was completed on a cyclone Cybex 530C stationary bike, Cybex arc trainer model 610A, or a Cybex treadmill 710. The general warm-up was followed by 1 specifically related to the testing protocol. Testing guidelines for the chest press adhered to the National Strength and Conditioning Association protocol (1). The chest press machine used for testing was the Cybex converging plate loaded chest press (model 5227-90). The subjects were instructed and shown the standardized lifting technique and range of motion, which required starting with a 90° bend at the elbows, finishing with arms straight. The independent arm mechanism on the machine allowed for 5 different arm adjustments to achieve a starting position of 90°. The seat adjustment had 6 positions to ensure that the subjects’ shoulders were in alignment with their elbows in the transverse plane. During each progressive set of the warm-up, the seat and arm positions were checked and, if needed, were adjusted to ensure adherence to the standardized testing form. A specific warm-up was completed with 5–10 repetitions with a light to moderate load. Two more similar sets of increasing load were completed. The final set required a maximal effort for 1–15 repetition maximums (RMs). If the subject was not able to achieve this requirement, a 2-minute rest was given, and the load was adjusted for an additional trial. The final number of RMs completed was then converted to a 1RM using the National Strength and Conditioning Association conversion chart (1). Posttesting in the chest press followed the same testing guidelines as the pretest.
Testing guidelines for standing broad jump followed protocol and procedures commonly used in field testing (14). A professional 30-m fiberglass tape was used for measurement. A hardwood aerobics room was used as the testing area. Packing tape was used to adhere the measuring tape to the floor, creating a takeoff line at the 0-cm mark. Students were instructed to keep both feet behind the line while the tester made sure that no part of the subject’s shoe or foot was on or past the 0-cm mark. The subjects were instructed to stand on the right side of the extended tape to be sure they did not step or land on the tape and so that the instructor (who stood on the opposite side of the tape) could have a clear unobstructed view of the takeoff and landing. The subject performed a countermovement and then jumped horizontally as far as possible beside the tape. The subject had to remain stationary long enough to show a controlled time to stabilization. The jump was recorded as a fault if the subject stepped backward or fell forward. The jump distance was measured from the heel of the foot that landed closest to the 0-cm mark. All 3 trials were measured, with the longest distance used (to the nearest 0.5 cm) for statistical analysis and for comparison. Posttesting in the standing broad jump followed the same testing guidelines as the pretest.
After pretesting, subjects began their workouts in a modern-day fitness center with motorized equipment and flat screen televisions. Subjects had 45 minutes to complete the exercise routine. Half of the subjects were advised to perform upper-body exercises while the other half started with lower-body exercises. In this way, there was no competition for the same machine, and waiting for exercise equipment was minimized.
The workout program was constructed using the principle of flexible nonlinear periodization. Subjects were allowed to adjust the workout intensity according to their mood, preference, and energy level. Early in the mesocycle, subjects had numerous workout choices that varied in RMs. Depending on how subjects felt on a particular day, they could choose, for example, a 5RM workout instead of one that was 20RM, and the SEC group was allowed to choose 10 seconds of modified maximal-effort cycling on the bike instead of 45 seconds if they so desired. However, toward the end of a mesocycle, subjects had fewer options. They eventually were required to complete the workouts that had been avoided earlier. Both groups completed the 13.5-week training program, which was divided into 4 mesocycles. The first mesocycle lasted 3.5 weeks, the second and third lasted 4 weeks, and the fourth mesocycle lasted 2 weeks (Table 1).
The first mesocycle included the Cybex leg press, Cybex prone leg curl, Cybex converging plate loaded overhead lift, Cybex converging plate loaded chest press, Cybex low row, and crunch-style sit-ups. Machine exercises were chosen to ensure the safe participation of all novice subjects. Two sets were completed for each exercise with RMs of 5, 8, 10, 12, and 15, totaling 476 repetitions. Cardio time (per workout session) was 15 minutes at an average rate of perceived exertion (RPE) of 6.8 on the revised Borg scale, which ranges from 0 to 10.
The second mesocycle added the following exercises to the training program: Cybex VR3 leg extension, Cybex fly, Cybex modular lat pull-down, Cybex 45° back extension, and supine leg raises. One set was completed for each exercise with RMs of 6, 7, 8, 9, 10, 11, 12, and 13, totaling 836 repetitions. Cardio time (per workout session) was 15 minutes, with an average RPE of 7.6 on the revised Borg scale.
The third mesocycle added only 1 exercise, lunges. One set was completed for each exercise with RMs of 10, 11, 12, 14, 16, 18, 19, and 20, totaling 1,356 repetitions. Cardio time (per workout session) was 15 minutes, with an average RPE of 8.7. No additional exercises were added during the fourth mesocycle. One set was completed on each exercise with RMs of 5, 8, 10, 12, and 15, totaling 520 repetitions, and cardio time (per workout session) was 15 minutes, with an average RPE of 8.4.
Only the SEC group used maximal-effort cycling as a part of their workout program (Table 2). The protocol for maximal-effort cycling was similar to laboratory Wingate testing (14). First, subjects were required to have completed a 10-minute general warm-up before the test. Subjects were then brought to the bike, and the seat height that ranged from 1 to 11 was set so subjects were comfortable and so that leg flexion and extension ranged between 90° and 180°. Subjects were asked to pedal as fast as they could momentarily and then pedal at a relaxed pace to wait for the test to begin. Subjects were then asked to pedal at a fast pace while tension was added, ranging from 1 to 21. When the subjects acknowledged that the tension was set at their preferred setting, they were asked to pedal at a very slow pace to get ready for the cycling, and tension was again reset to level 1 (the lowest possible resistance). After 1 minute of slow pace and a tension setting of 1, subjects were given a 5-second warning before the cycling began. During these 5 seconds, subjects were instructed to increase cycling speed, which took ∼2.5 seconds. When top speed was reached at the 2.5-second mark, tension was added by the instructor. The instructor was able to set the bike tension from 1 to 21 in 2.42 seconds. Therefore, 5 seconds of total adjustment time was all that was needed to coordinate speed and tension. When top cycling speed was reached and tension was set, the workout began. On subsequent cycling bouts, students were not given verbal or visual instruction because they were already familiar with the testing setup and execution. Test duration ranged from 10 to 45 seconds. Subjects were given 2 minutes of rest between sets.
All cycling was completed on a Cybex cyclone model 530C stationary bike and followed a flexible nonlinear protocol. Students were allowed to perform the cycling during any point in their exercise routine and were allowed to choose between several time durations ranging from 10 to 45 seconds, and also several intensities ranging from 4 to 10 on the 10-point RPE scale. Subjects in the SEC group performed maximal-effort cycling 16 times at an RPE of 10: twice at 45 seconds in the first and forth mesocycle; twice at 10, 15, and 20 seconds in the second mesocycle; and 4 times at 15 seconds and twice at 20 seconds in the third mesocycle. On average, subjects in the SEC group performed ∼1 more minute of exercise (per workout session) compared with the SE group. The SEC group performed a grand total of 12.45 minutes of cycling over the 13.5-week program (Table 2).
During the 13.5-week workout program, the subjects were required to monitor their diet, sleep hours, stress levels, and pre-workout and post-workout energy levels on the days that they exercised. A simple eating scale was devised so that students could rate their diet in comparison with the U.S. Department of Agriculture MyPyramid plan (28). Subjects rated their diet as “poor,” “okay,” or “excellent” depending on the inclusion or exclusion of ≥1 food groups. Subjects categorized their average daily assessment as “okay.” Adequate sleep was stressed as being important for recovery from exercise. The number of sleep hours ranged from 2 to 8 hours, with an average of 5.7 per night. The daily stress scale score average was medium, as rated on a scale of low, medium, and high. Subjects’ energy levels were self-monitored using a 10-point scale. Zero implied no energy and 10 reflected maximum energy. The average pre-workout energy level score was 5.8 and the average post-workout energy score 4.6 (Table 3). To encourage subjects to keep truthful and accurate records, they were not penalized in any way for recording poor nutrition levels or inadequate sleep hours.
To determine if both groups were the same at the start of the study, pretest scores on chest press and standing broad jump were compared between groups using independent t-tests. After the initial analysis, a mixed design analysis of variance was used to analyze a between (experimental vs. control) and within (bench press vs. standing broad jump) experimental design. The level of significance was set a priori at p = 0.05 for analyses using IBM SPSS Statistics version 19 (SPSS, IBM, Armonk, NY). Power was also calculated to determine the percent of variance in the dependent variable that can be explained by the independent variable. Statistical power was calculated for standing broad jump and for seated chest press. The t-tests and descriptive statistics, including means and ranges, were calculated to compare the SE and SEC groups.
Independent t-tests indicated that there was no statistical difference on pretest scores on standing broad jump, t(18) = 0.36 (not significant), and seated chest press, t(18) = −0.22 (not significant). Therefore, the 2 groups were considered to be equal at the start. On analysis of variance, the investigators’ hypothesis was incorrect; there were no significant differences when comparing groups on chest press performance (F = 33.7, p = 0.704) and standing broad jump performance (F = 11.1, p = 0.060; Figure 1).
Statistical power was calculated at 0.45 for standing broad jump and at 0.27 for seated chest press. Descriptive statistics were calculated on the dependent variables to determine the distributional characteristics of the SE and SEC groups; means (Table 4), ranges (Table 5), and total workout times (Table 1) were tabulated. Table 2 shows the mean and total sprint cycling times for the SEC group. Paired sample t-tests supported the investigators’ expectation that the SEC group would show significant improvement in the standing broad jump, t(9) = −3.25 (p = 0.01), and chest press, t(9) = −3.83 (p = 0.004), and that the SE group would improve in chest press, t(9) = −4.62 (p = 0.001). The investigators were surprised, however, to see that no significant improvement was made in the standing broad jump in the SE group: t(9) = −1.17 (not significant). The same tester in this study also demonstrated high intraclass correlations for seated chest press (r = 0.99) and standing broad jump (r = 0.98) using the same-day test-retest method in a previous study (23).
After an extensive review of literature, it was determined that this study was the first to combine concurrent training, flexible nonlinear periodization, and maximal-effort cycling in the same exercise program. The results of the experiment indicated that there was no difference between the SE and the SEC groups. Intense anaerobic glycolytic training on a stationary bicycle yielded no significant effect on dependent measures of the standing broad jump and chest press.
The most significant piece of evidence supporting the hypothesis was the trend toward improved standing broad jump performance in the SEC group (Figure 1). This was considered substantial evidence especially considering that concurrent training has been shown to attenuate (8,9,29) lower-body leg torque and power. An initial explanation that the trend toward improved standing broad jump performance could be related to the principle of specificity (training the lower body using a maximal-effort cycling protocol could improve lower-body performance) was discounted. A careful examination identifies that the spinning motion of the legs might be too general and not the same as the ground reaction forces that occur in the standing broad jump. Although the anaerobic maximal effort tests cycling power, it might lack specificity with respect to eliciting a stretch reflex generated by massive ground reaction forces. Alternately, the new system of training used in the SEC group, which used flexible nonlinear periodization and emphasized training the anaerobic, glycolytic, and aerobic energy systems, may be responsible for the trend toward significance. In future studies, adding small amounts of anaerobic glycolytic training in the form of maximal-effort cycling lasting from 10 to 45 seconds may result in significantly improved performance over single-mode training programs.
Factors not controlled for that may have contributed to the nonsignificant difference between the SE and the SEC groups include the hours of sleep each group had completed, their self-reported nutrition scores, and their self-reported stress levels (Table 3). For example, the SEC group reported 5.65 hours of sleep the night after their workout compared with 6.03 in the SE group. It is possible that the SEC group was not getting enough recovery to allow positive physiological changes to occur. In addition, the maximal-effort cycling on a stationary bicycle performed by the SEC group may have created a greater metabolic demand requiring even more sleep.
Self-reported nutrition scores using MyPyramid as a standard for healthy eating indicated (Table 3) that the SEC group had better nutrition intake (2.06) than the SE group (1.89). It is possible that better nutrition habits may have supported positive physiological changes in the SEC group even though they received less sleep. Alternately, self-reported stress levels in the SEC group were higher than those reported in the SE group. This could also be a reason why the SEC group failed to reach statistical difference in the study. Higher stress levels, combined with less sleep and the additional workload of maximal-effort cycling, may have restricted the posttest performance of the SEC group.
Although improvement of each group from pretest to posttest was not the main focus of this research, it did occur. Upper-body strength improvement over time is a common result from a regular physical training program (26) and was found in both the SE and the SEC groups (Table 4). It is also a common finding in a number of other studies that used a concurrent training protocol and dependent measures of upper-body strength (6,7,15). In 1 study (9), the sport of handball was used as a training stimulus; others used stationary cardiovascular methods such as the treadmill and bicycle as the aerobic portion of the training protocol (7,15). None of them, however, used flexible nonlinear periodization training protocols.
The investigators were surprised, however, that the SE group did not significantly improve, over time, in the standing broad jump. The average pretest score in the SE group was 171 cm at pretest and 176 cm on posttest (Table 4). These results are similar to those of the other concurrent studies in which leg performance was poor (13,15), or even deteriorated from pretest measures (8,9). Because the SE group did not execute rapid powerful movements on a stationary bicycle, the fast-twitch muscles may not have been adequately trained.
In summary, the creation of this study was based on combining several training methods and theories that resulted in positive performance outcomes. The principles of training (1,5,8,17,21,24), flexible nonlinear periodization (23), multilateral training (8), GAS (25), concurrent training (7–9,13,15), and the concept of energy system interdependence (24) all supported our concept for the training program used in this study.
The notion that each energy system (anaerobic, glycolytic, and aerobic) depends on the other prompted the investigators to include 3 distinctive modes of training (traditional weight training, treadmill running, and maximal-effort cycling) in the SEC group. The unique physiological and chemical interactions that exist when varied and multiple exercise stressors are placed on a subject can be highly complex and interrelated. There may need to be a particular alignment of training variables and a very small window of opportunity within which an SEC training program is effective. Specific ratios of frequency, intensity, duration, and type of exercise may need to be partitioned and strategically balanced. For example, 100- and 200-m world record sprint champions may be successful because they partition their training correctly. The largest amount of time might be spent training the short-duration anaerobic energy system, a moderate amount of time training the glycolytic system, and the least amount of time training the longer term aerobic system. Finding the right combination of training variables should augment the limiting factor in sports performance.
Future studies of this kind might examine within-workout order when multiple energy systems are trained. For example, should one energy system (such as the aerobic system) be trained first in the training session, and how soon after should the next energy system be trained? Should a heavy set of squats be followed with another set of heavy squats, or 30 seconds of maximal-effort cycling? There is virtually no limit to the combinations of training variables that can be manipulated and arranged in a training program.
Additional research suggestions include a longer study with more subjects to increase statistical power. Also, adding nontraditional training movements such as kettle bells and exercise bands might provide a unique independent variable that can allow the maximum stimulation, recovery, and overcompensation of a person’s physiological makeup and result in superior performance. Choosing different posttests might also accurately identify significant training changes. For example, other tests of upper-body and lower-body strength could include the Margaria stair climb, vertical jump, and leg press.
As a final point, the thrust of this research project was to emphasize the importance of reviewing effective training methods and theories to continually seek improvement and enhancement of training theory. By combining previous knowledge with new techniques and original theoretical models, practical applications can be formulated. Although an individual training script might be beneficial to one specific athlete, a general training plan or a new theory of training can help everyone—participants, athletes, or even the general public—as long as appropriate consideration is given to each person’s individual differences, fitness level, and safety.
An exercise professional can take confidence that a concurrent flexible nonlinear training program combined with maximal-effort cycling can increase strength and power in healthy individuals. A reasonable starting point in initiating such a program would be to combine 3 modes of training into 1 program. The first component would be to begin a resistance training program using 2 multijoint lower-body machines, 3 multijoint upper-body machines, and 1 abdominal exercise. The second would be to complete 15 seconds of maximal-effort cycling at high speed on a stationary bike. The third component would be to begin with easy to moderate cardiovascular conditioning on a treadmill, bike, or elliptical glider for 15 minutes, twice a week. All 3 components would start off at an RPE of 2 (fairly light) and would be combined into one 45-minute block of time to be completed twice a week with at least 1 day of rest between training days. It is important to remember to use flexible nonlinear periodization considerations to evaluate the readiness of trainees. It is equally important to ask trainees if they feel tired on a particular day so a difficult workout can be replaced with an easier one. The more difficult workout can then be completed on a day when the trainees have more energy.
We thank Drs. Michele Hirsch, Esther Klein, Gerard Shaw, and Steve Lipson for their time and help with this study.
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