Concurrent training is the idea of combining both endurance training and weight training into 1 program (1). Although research on this topic is limited, the majority of studies illustrate that during concurrent training, athletes are prone to either a reduction or no improvement in strength gains or a reduction or no improvement in endurance gains, compared with training for each separately (3,4,6,7,10,12). However, some studies are now confirming that concurrent strength and endurance training are more effective in improving athletic performance than are either endurance or strength training separately (1,8,9,13). These contradictory findings are difficult to interpret for endurance athletes looking for enhanced concurrent training programs. One group of athletes in particular, rowers, rely heavily on both power and endurance to excel at their sport. However, the most effective way for them to train for improved athletic performance remains unclear.
Despite the aerobic energy demands during rowing, anaerobic factors play an important role in an oarsman's overall success. Hickson et al. noted that certain types of endurance sports, particularly those requiring fast-twitch fiber recruitment, can be improved by strength training supplementation (8). Gains to this system could be useful during starts, surges in pace, and sprint finishes. Nonetheless, many rowing coaches believe, because rowing is 70-80% aerobic (11), that if the training stimulus does not increase their athlete's O2max then that training stimulus is not specific to rowing and should not be continued, because it may deter from the primary source of performance gains. However, there is little empirical evidence that illustrates that resistance training will decrease or increase a rower's performance, creating controversy for concurrent endurance and resistance training for oarsmen.
Unfortunately, this lack of research on the technical and physical demands of rowers, and potentially improving them through weight training, leaves professionals still questioning the idiosyncrasies of the sport, because the physiological demands of a rower during a 2,000-m race are quite intense. During the 6- to 7-minute all-out effort race, the rower works anaerobic alactic, anaerobic lactic, and aerobic systems to their maximal capacity. Even though aerobic fitness accounts for the majority of rowing performance, muscular power and maximum strength also play a significant role in rowing success. Because of the components of hydrodynamics, to amplify oar velocity, oarsmen must increase their muscular force to overcome increased water resistance, illustrating muscular strength as a limiting factor in hull speed (15).
With regards to rowing-specific weight training protocols, 3 researchers have proposed diverging viewpoints that lead to the development of the current study. McNeely supports using high percentages of 1RM, usually between 85 and 95% or less than 6 repetitions, resistance training (5,11). However, unlike McNeely et al., Ebben et al. compared and propose moderately high repetitions (67-85% or 6-12) and high repetitions (<67% or 15-32) to effectively increase performance (5). McNeely and Ebben both support resistance training for rowers but disagree on the optimal mode of training, whereas Bell et al. disagree with both McNeely and Ebben, stating that an emphasis on resistance training is useless in developing rowing prowess because it restricts the volume of specific training for the oarsman (2).
Overall, the conflicting weight training research along with the opposing concurrent training research makes it difficult for rowers to find an optimal training method. Therefore, the purpose of this study was to test the effects of concurrent endurance and resistance training while comparing both high- and low-load resistance training protocols. Two hypotheses were developed from the review of the literature: (a) both concurrent endurance and resistance training groups will demonstrate greater improvements on 2,000-m rowing ergometer times than the nonweight training control group; (b) the high-load group will demonstrate greater improvements on 2,000-m rowing ergometer times than both the low-load group and non-weight training group.
Experimental Approach to the Problem
As previously stated, concurrent endurance and resistance training has been shown to increase, decrease, or show no alterations in athletic performance. To determine the effects of combined endurance and resistance training on 2,000-m rowing ergometer times (dependent variable), 18 male rowers were randomly and equally divided into 3 groups (independent variable) consisting of a control group (CON), high-load and low repetition (HLLR) weight training group, and a low-load, high-repetition weight training group (LLHR). Pre and post 2,000-m rowing ergometer tests were performed for all subjects, with the 2 experimental groups performing resistance training for 8 weeks as an intervention. All subjects performed identical weekly twice rowing workouts for 50 minutes per session in addition to their regularly scheduled team practices.
The subjects consisted of 18 male rowers from Grand Valley State University (GVSU). Participants had diverse rowing backgrounds and ranged in years of rowing, rowing preferences (starboard or port), height, weight, and ages. The athletes in this study have had great success in the rowing community, and the subject pool included 2 first team All American ACRA Inductees, third place-American Collegiate Rowing Association (ACRA) National Championships Men's Varsity Eight, and fourth place-Head of The Charles Men's Collegiate Eight. A qualifying variable for the participants was that they were full-time rowers and on the official team roster. Before beginning the study, athletes had been performing unsupervised training for the previous 3 months. This training included resistance training, rowing, and various crosstraining types of activities. The investigation was approved by the Institutional Review Board for use of Human subjects at the George Washington University, before data collection. Participants were recruited via an informational session held by GVSU's head rowing coach, and all participants completed written informed consent documentation before actively engaging in the prescribed training study.
Subjects were randomly and equally assigned to 1 of 3 groups, before the research began, by randomly picking names from a hat. As stated previously, groups were labeled CON, HLLR, and LLHR. Subjects in the resistance training groups strength trained twice weekly for approximately 50 minutes per session, and all subjects performed identical rowing workouts twice weekly for approximately 50 minutes per session, all in addition to their regularly scheduled practices. All subjects underwent a 2,000-m rowing ergometer test before and after the 8-week resistance training and rowing intervention period.
The athletes were evaluated on their pre and post 2,000-meter rowing ergometer times using a concept 2 model D or C indoor rowing ergometer. This machine simulates the rowing stroke and displays individualized data such as stroke rate, wattage, time, average 500-m splits, and caloric expenditure. The concept 2 models D and C can both be calibrated by using specific drag factors that increase or decrease the amount of resistance produced by the flywheel. Because each machine can be calibrated to the same resistance, there is no difference between the 2 in collecting individualized data. The overall time to perform the 2,000-m rowing ergometer test was used as the dependent variable for the study.
Rowing requires the use of all major muscle groups: starting with the legs then to the back and then finishing with the arms. The workout program developed for this study was designed to strengthen each of the major muscle groups used for rowing. Both free weights and resistance training machines were used in the training groups. Subjects' weight scores were recorded as the amount lifted for each set. For both the resistance and rowing ergometer training, athletes used a supplied journal to monitor their training progress.
Before the commencement of the 8-week training programs, athletes were evaluated on a 2,000-m rowing ergometer test at GVSU's rowing training center; the ergometers were calibrated to the 130-drag factor. The test took place in the morning, and rowers did not fast before the test and were allowed to consume their usual morning breakfast foods and liquids. Athletes arrived at the rowing training center 45 minutes before the test and warmed up on the ergometers for 10 minutes. The warm-up consisted of 5 minutes of easy rowing immediately followed by 2 30-second race pace pieces, with each piece separated by 2 minutes of easy rowing. The rowers were given 5 minutes before the test started to stretch and to drink water. The rowing ergometers were set at 2,000 m and counted down to 0 m, with athletes using any monitor display setting they felt comfortable with. There was no capped stroke rate and athletes were expected to exert maximal effort for the duration of the entire test. All athletes were highly verbally encouraged during the test.
Resistance Training Protocol
Athletes in both the HLLR and LLHR training groups trained for 8 weeks, completing 2 workouts per week. The 2 workouts were comprised of exercises that did not change during the 2 months of training (Table 1). However, the set and repetitions changed weekly with repetitions becoming lower each week (Tables 2 and 3). The first month was identical to the second month with regards to training frequency, exercises, and set and repetition assignments per week.
Repetitions decreased throughout the first month of training; therefore, athletes were expected to increase the load for each set, of every exercise, every week. During the first month, a 5-lb increase was expected for every set of every exercise for each week of training. If athletes could not achieve the 5-lb increase, they were expected to maintain the previous load used the preceding week. During the fourth and eighth weeks of training, athletes were required to outperform their previous best for that prescribed repetition maximum (RM) by at least 5 lb. Also, in every session, athletes were required to record their total weight for each exercise; total weight was found by adding up the loads used for each set.
The following month, athletes were required to exceed their previous total weight records from month 1. This was achieved by increasing each set of every exercise by at least 5 lb or more. If athletes could not achieve the 5 -lb increase, they were expected to maintain the previous load from the preceding month. Ideally, loads continuously increased throughout the 8 weeks of training. At the conclusion of the 8-week training program, athletes were given a recovery week to rest from the 2 months of training. This time was of importance, as it allowed restitution and the development of a supercompensated performance baseline (15). During the recovery week, athletes were encouraged to only participate in the prescribed team schedule set by their coach.
The athletes were required to work to maximal voluntary contractions during their weight lifting sets, that is, hitting failure on their last repetition. Because of the high level of fatigue achieved from each set, athletes took 2 minutes of rest between each exercise. Athletes were informed by their coach on how to properly perform RM weight training. The varsity rowers had previous resistance training experience with the prescribed exercises and were able to self-determine the proper loads for the required RM. The coach instructed his athletes to use 1 or 2 warm-up sets (10-12 reps of light to moderate weight) before executing any heavy lifting; the warm-up set was not logged and was not added to the total weight for that exercise. Each athlete only recorded the performed RM load for each set, of every exercise, in the training log provided by the coach.
Rowing Training Protocol
All subjects performed a total of 16 rowing training sessions during the 8-week training period, using either a rowing ergometer or on the water. All workouts were of long duration and were intended to be performed 18-25 seconds above the athlete's maximum 2,000-m average 500-m split. During ergometer training, the drag factor was set at 130. Each week was composed of 2 training sessions, and at the beginning of week 5, the workouts started over and repeated themselves from week 1. The athletes recorded their average 500-m splits, for each workout, in their training log provided by the coach.
The primary outcome variable of interest was 2,000-m time (seconds). Univariate statistics (mean ± SE; %) were first generated on the study variable. Within-group differences in the study outcomes before and after training were tested with paired t-tests. Differences in training-related improvements (time and percent change) among the 3 groups were tested using a 1-way analysis of variance with repeated measures. Statistical significance was set at an α-level of <0.05.
The 3 groups were similar in height, weight, age, and years of rowing (Table 4). Athletes participating in both the HLLR and LLHR groups showed improvements in overall upper body and lower body strength, as the LLHR group increased total weight for all exercises by 367 lb and the HLLR group increased by 125 lb. The LLHR group experienced a 9.44% relative increase in overall body strength, whereas the HLLR group experienced a 2.02% relative increase in overall body strength.
All groups showed statistically significant improvements in 2,000-m rowing ergometer times after 8 weeks of training (Table 5). The HLLR group experienced a −3.4% change in performance, whereas the LLHR group had a −3.1% change and the control had a −2.8% change (Figure 1). Individual changes in 2,000-m ergometer rowing performance are shown in Figures 2A-C. Intergroup analysis did not show a statistical difference between the 3 groups (p < 0.96).
Groups were then stratified by years of rowing to determine whether rowing experience served as an effect modifier to the relation between training method and training-related improvements among the groups; however, the results were unchanged (data not shown).
This study integrated 2 popular weight training methods that are used by a multitude of rowers. One method focused on developing muscular endurance and the other focused on developing maximal strength. Unlike Ebben et al., we focused on developing our rowers with distinct high loads and distinct low loads (5). This particular approach allowed for the evaluation of effects of 2 different weight training methods on rowing endurance training, specifically on 2,000-m rowing ergometer times. The goal was to determine if the specific weight training improvements would carry over and show significant differences during rowing ergometer testing and increase overall rowing performances. Our results illustrated that athletes participating in the weight training protocols became better resistance trainers over the 8-week cycle, but did not become better athletes on the rowing ergometer, based on overall percent change, than those athletes who did not weight train. Even though the athletes were stronger, their generalized strength gains did not increase rowing performances, regardless of the weight training method used.
These conclusions agree with those of Bell et al. who also found similar results with experienced male rowers who trained with high- and low-velocity resistance training programs (2). Our results show that the supplemental effect of resistance training does not substantially decrease an athlete's rowing ergometer time when compared with a control group. These results disagree with those of Balabinis et al., who stated that concurrent endurance and strength training is more effective than training the 2 aspects separately (1). However, Balabinis et al. trained basketball players, whereas we were training rowers, who typically have more aerobic aptitude. Our study did not illustrate a synergistic training effect while simultaneously combining endurance and resistance training when developing varsity oarsmen.
Dudley et al. also found similar results where concurrent endurance and strength groups showed changes in peak cycle ergometer O2 of similar magnitude and linearity as the endurance-only group (4). They concluded that performance of both modes of training does not alter the adaptability of the factors that govern increases in peak cycle ergometer O2. Our study illustrates that adding resistance training to an endurance-oriented sport is not going to modify aerobic power induced by endurance training only. However, Hickson et al. claim that strength training might be compatible with improving performance in endurance sports that require fast-twitch fiber recruitment (8), such as rowing, possibly because of the increased contractile protein per cross-sectional area, but this idea was not supported by the current study.
According to Ebben et al., periodized resistance training improves endurance performance in women rowers; resistance training adaptations are similar among genders (14), regardless of its effects on O2max (5). Our results show similarities because both the high- and low-load groups showed decreases in 2,000-m rowing ergometer times after 8 weeks of concurrent endurance and resistance training. Their high-load group had a decrease of 7 ± 8 seconds, and their high repetition group had a decrease of 4 ± 6 seconds. These findings are comparable to our results, because our high-load group had a decrease of 15 seconds and the low-load group had a decrease of 12 seconds on their posttesting averages. However, our study adds to Ebbens' findings by including a control group, which demonstrated an 11-second decrease.
The control group allowed us to evaluate the effectiveness of the HLLR and LLHR groups. Although the 2 groups both had statistically significant improvements in rowing ergometer times, their improvements were not statistically greater than the control's or each other's, illustrating that both modes of resistance training allows for increased rowing performance, but does not deliver a synergistic effect that is superior to rowing endurance training only.
Although, the overall model was not statistically significant, the trend in the data was in the hypothesized direction. For example, the control group had an 11-second decrease in overall mean time, whereas the low-load group demonstrated a 12-second decrease, and the high-load group decreased by 15 seconds-this latter difference being nearly equivalent to a boat length during a 2,000-meter sprint. It is likely that the attrition of 3 athletes (2 from the control and 1 from the LLHR group) and the overall low number of subjects available in this study resulted in a lack of statistical power to substantiate the trend toward a greater performance in the resistance training groups. In addition to the small sample size, the length of the study was only 8 weeks, which may not have been long enough for some athletes to develop the changes under investigation. Depending on their degree of weight training before the study, athletes may have developed strength primarily through a neural adaptation, and not peripheral adaptations at the muscle. Therefore, the strength gains seen in these athletes would likely have been greater if the study were long enough to allow for physiological changes at the myofiber level. Conversely, 8 weeks may have been too short to see strength changes in subjects who participated in chronic resistance training. A longer study design would have allowed for more complete training adaptations in both of these situations.
Nonetheless, training specificity plays a crucial role in developing competitive endurance athletes and using modes of training that do not have a great return on investment should be avoided and replaced with specific exercises that enhance performance, such as increasing the amount of training time on the rowing ergometer to enhance aerobic endurance, O2max and lactate thresholds. Therefore, training the actual movement itself rather than individual muscles, through resistance training, is most beneficial. However, competitive endurance athletes are still known to incorporate some types of resistance training into their regimens, but caution should be used to avoid excessive fatigue and injury (7).
Ideally, a study that follows all athletes through chronic training would be optimal from a quantitative analysis standpoint, as 16 weight training sessions may not have been enough to see any specific results. Additionally, a 5-day rest period after the completion of strength training may have been inadequate to allow for complete realization of strength because of delayed transformation, and this may have marginalized the results of the final 2,000-m rowing ergometer test. The weight training groups in particular were training an extra 2 h·wk−1; therefore, they may have needed more time to realize their supercompensated baseline when compared with the control group.
In the current study, the combined use of resistance training and rowing did not result in any statistical improvement in 2,000-m rowing ergometer times over rowing alone. However, the groups that used resistance training and rowing enjoyed faster rowing times, with the high-load low-rep group showing the greatest improvements. Although not statistically significant, the high-load resistance training group experienced a decrease in rowing time of 2.8 seconds more than the control group, and 2.2 seconds more than the low-load resistance training group. The authors feel that the practical significance of this decreased rowing time in the high-load weight training groups is profound, and warrants the use of high-load resistance training for the oarsman. Nonetheless, it is advised that the majority of training for rowers consist of actual rowing, with resistance training serving as an adjunct to that training. Further work needs to be done to determine the optimal resistance training prescription for rowing.
The authors would like to thank the rowers and coaches from GVSU for donating their time, effort, and resources for the completion of this study. The results of the present study do not constitute endorsement of the Concept 2 indoor rower by the authors or the NSCA.
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