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Original Research

Comparison of Physiological Variables Between the Elliptical Bicycle and Run Training in Experienced Runners

Klein, Ian E.1; White, Jason B.2; Rana, Sharon R.1

Author Information
Journal of Strength and Conditioning Research: November 2016 - Volume 30 - Issue 11 - p 2998-3006
doi: 10.1519/JSC.0000000000001398
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Abstract

Introduction

Running is a highly popular mode of exercise with over 19 million race finishers in 2013 (31). Despite these numbers, runners have seen injury rates up to 79% within a 1-year span (37). Most commonly experienced injuries for runners are overuse injuries (14), which have been linked to the repeated ground impact forces that occur during running (13). Overuse injuries force runners to partially or fully terminate their run training (RT) (21,39). Detraining, or the reversal of physiological adaptations and performance abilities, can consequently occur (26). Runners seek nonimpact cross-training methods that have the ability to produce running-similar movements and high-intensity efforts to prevent decrements in fitness and performance, whenever detraining is likely to occur (26,34).

To prevent detraining from occurring, nonimpact cross-training methods are often used in hopes of maintaining fitness and performance levels without incurring further injury. For a runner, cross-training can encompass any alternative form of exercise implemented into a runner's training program apart from running, such as cycling, swimming, or using an elliptical trainer. Cycling and swimming have been unable to elicit maximal oxygen consumption (V̇o2max) values similar to treadmill running in trained runners (34,40) or provide adequate training adaptations to maintain ventilatory threshold (VT) (15,34). Exercise using an elliptical trainer has been shown to improve physiological variables, such as V̇o2max, in previously moderate-fit, untrained populations compared with treadmill running (9). This has also been seen in recently trained runners of 4 weeks (18). However, it is suggested that the elliptical trainer might not be effective in improving physiological variables or maintaining 3,000 m time trial (TT) times in long-term trained runners (16).

Other low impact cross-training methods have been designed to imitate similar running movements in an attempt to maintain physiological and performance variables in experienced runners. In a case study, the antigravity treadmill training, which used treadmill running at 50–95% body weight, suggested maintenance of performance abilities after a period of injury for 1 collegiate distance runner (35). Deep water running (DWR) was also performed in the athlete's training which may have contributed to the observed results. Deep water running has been seen to elicit similar muscle activity in deep water (22) compared with running. However, V̇o2max, heart rate (HR), and ventilation (VE) values during DWR have been unable to reach levels seen during treadmill running in trained runners (8,33). The oxygen consumption (V̇o2) and HR at a runner's VT were also observed to be greater during treadmill running compared with DWR (12). Over a 6-week training period, DWR has been shown to maintain V̇o2max, VT, running economy (RE), and run performance in trained male runners (38). Exercise with an outdoor, running-similar, low impact, and physiologically similar cross-training machine is ultimately desired.

The elliptical bicycle (EBIKE) is a new modality of nonimpact cross-training which has been developed for runners to imitate outdoor running. The previously unresearched EBIKE is marketed as a nonimpact and running-similar exercise modality (28). The EBIKE was engineered as a hybrid between an elliptical trainer and a bicycle with modifications intended to emulate the running motion in hopes of eliciting running-similar training adaptations. The EBIKE has 4 adjustable stride lengths, from 41 to 64 cm, which are similar or greater in length compared with various models of the stationary elliptical trainer (3,28). Handlebar heights on the EBIKE also adjust from 127 to 147 cm to best fit a rider's height to imitate their preferred running body position. Another major difference between these modalities is that the EBIKE includes a steeper pedal angle during the recovery phase that positions a rider's toe downward. This modification is designed to allow the rider's leg to recover from the most posterior position and travel into the most anterior knee drive position in a running-similar fashion. This is designed to facilitate greater knee flexion and ankle plantarflexion movements. Second, the absence of a fly wheel on the EBIKE prevents momentum from assisting the rider in propulsion of the EBIKE. Foot contact with foot pedals occurs at all times and riding can occur outdoors, as opposed to DWR or antigravity treadmill training. Proper EBIKE balance and steering are also necessary for riding, which aims to recruit weight-bearing stability musculature similar to those muscles used when running.

To date, the training effects of the EBIKE compared with running on physiological and performance variables have yet to be studied. This information would be of great importance and interest for injured runners who are unable to run and also for healthy runners who aim to attenuate losses in physiological and performance factors during scheduled nonrunning periods of recovery. The purpose of this study was to compare V̇o2max, VT, respiratory compensation point (RCP), RE, and 5,000 m TT times between 4 weeks of EBIKE-only and run-only training. It was hypothesized that these variables would not be different between groups.

Methods

Experimental Approach to the Problem

To compare elliptical bicycle-only training (ET) with run training (RT), a randomized, crossover, training study design using matched 4-week exercise training periods of ET and RT in experienced runners was implemented. Four-week training periods were chosen to reflect a length of time when detraining can occur for experienced runners (4,26). V̇o2max, VT, RE, RCP, and TT times were the measured variables at each testing point and were selected because of their high importance as fitness markers and predictors of running performance (24). The TT was used as a definite measure of running performance (27). Exercise training periods of either ET or RT were matched for frequency, duration, and relative intensity. Intensity was measured using HR zones, which included easy (HR range = HR below VT), medium (HR range = HR above VT to HR at RCP), and hard (HR range = HR above RCP to HRmax) as determined from each subject's V̇o2max test. Prescribed percentages of exercise training in these zones were 80, 15, and 5% for easy, medium, and hard, respectively, in accordance with typically prescribed, evidence-based running programs that aim to improve aforementioned physiological and performance variables (10,32).

Subjects

This study included 12 (N = 12) subjects, including 6 men (n = 6) and 6 women (n = 6), ages 19–31 (average 22.33 ± 3.33 years). Subjects were healthy and experienced runners with an average body mass index (BMI) of 21.54 ± 2.29, body fat percentage (BF%) of 10.68 ± 4.79%, and running experience of 9.25 ± 4.53 years. Subjects averaged 4.46 ± 1.09 total runs per week with an average of 37.74 ± 11.04 km·wk−1, and 2.17 ± 1.37 high-intensity runs per week in the 2 months before volunteering for this study. Table 1 displays subject characteristics and training history. A power analysis was conducted to calculate the proper sample size for this study using G*Power 3.1.2 (Germany). Using a power of 0.80 and α of 0.05, with an effect size of 0.20, the required number of subjects was 12 for significance. Smokers and those with diseases or injuries that limited their ability to perform vigorous exercise were excluded. Subjects were excluded if they had any orthopedic injuries in the 3 months before this study that prohibited them from running for more than 6 consecutive weeks during that time frame. No subjects had any previous EBIKE experience before this study. Previous recreational bicycling, elliptical riding, or swimming activities were reported by a total of 7 subjects at a frequency of 4 or less times per month. This study was approved by the Institutional Review Board for Human Subjects. All subjects were informed of the benefits and risks of the investigation before signing an institutionally approved informed consent document to participate in the study.

Table 1.
Table 1.:
Subject characteristics and training history (mean ± SD).

Exclusionary conditions included heart disease, pulmonary, metabolic, or other conditions that could influence the inflammation response, including Crohn's disease, severe arthritis, cancer, or a previous heart attack. Subjects who were pregnant were excluded from this study. Blood pressure (BP) equal to or greater than 140 mm Hg systolic and 90 mm Hg diastolic was considered high BP (36) and warranted exclusion from this study. Those on BP medications were also excluded from this study. In addition, a subject's BMI and BF% were used as methods for determining a healthy subject. Subjects were required to have a BF% within the 50th–99th percentile for their respective sex and age group (36). Subjects were included if their V̇o2max values were equal to or greater than the 90th percentile values for their sex and age group (36). Average V̇o2max values were 57.92 ± 9.68 ml·kg−1·min−1.

Procedures

Physiological and performance assessments were completed over 2 testing sessions. Subjects were asked to avoid vigorous exercise and alcohol consumption 24 hours before these testing sessions as well as caffeine and food intake 3 hours before each testing session. Each subject underwent inclusionary and physiological assessments during an initial testing session, including a health history questionnaire (HHQ) and running history questionnaire (RHQ). Resting HR was measured using a HR monitor (Polar, Lake Success, NY, USA) and was determined as the lowest HR seen after the subject rested in a seated position for 5 minutes. Blood pressure was determined using a sphygmomanometer and an appropriately sized BP cuff. Height was measured using a stadiometer and was measured to the nearest tenth of a centimeter. Weight was measured using an electronic scale in kilograms. Next, in the controlled exercise physiology laboratory, a body composition measurement was performed using Lange skinfold calipers (Beta Technology, Ann Arbor, MI, USA) (30,36). Body composition, through BF% measurement, was performed using a 7-site measurement protocol and included skinfold sites at the chest, triceps, subscapular, abdominals, thigh, and suprailiac. The same trained researcher performed this protocol on each subject throughout the study. Body fat percentage was calculated using a sex-specific calculation (36).

During the same testing session, a graded V̇o2max treadmill test (GXT), using a motorized treadmill (TMX-425; Full Vision Inc., Newton, KS, USA) and calibrated metabolic cart (Truemax 2400 Metabolic Measurement System; ParvoMedics, Sandy, UT, USA), was used to determine V̇o2max, VT, RE, and RCP. After a 5-minute warm-up period on the treadmill, subjects were fitted for headgear, a mouthpiece, and nose clip. All subjects were given instructions on the use of the 15-point (6–20) Rating of Perceived Exertion (RPE) scale (2). Subjects were also instructed to provide a maximal effort during this test and to straddle the sides of the treadmill when they decided to stop. The first and second stages were set at speeds of 2.68 and 3.13 m·s−1, respectively, and a 1% incline. These treadmill speeds were chosen to ensure a steady state was reached below a subject's VT. Without knowledge of each subject's VT before the first GXT, 2 conservative speeds were chosen to ensure these steady-state measurements could be taken. Each subject displayed VT measurements at speeds above these first 2 stages. The first 2 stages were 3 minutes in duration to ensure steady-state values were obtained for calculation of RE. A subject's RE was defined as the milliliters of oxygen ventilated per kilogram of body weight for 1 kilometer (milliliter per kilogram per kilometer) at a given running velocity. This measurement was averaged over the last 1 minute of these 3-minute stages after a steady state had been achieved. The remaining stages were 1 minute in duration and individualized for each subject. These stages were gradually increased each stage no greater than 0.45 m·s−1 and 2% incline until volitional exhaustion occurred. Heart rate was monitored at all times and recorded every 30 seconds.

At the cessation of the GXT, the fitted headgear, mouthpiece, and nose clip were then removed, and subjects remained seated until a finger-prick blood sample was taken. This sample was used to measure blood lactate concentration 5 minutes after the cessation of the treadmill test. Subjects were then able to perform a walking or running cool down. Immediately after the GXT, the subject's RPE was recorded for the whole, upper, and lower body (2). A valid V̇o2max test occurred when 3 of the following 5 criteria were met: a plateau in V̇o2 or increase less than or equal to 0.15 L·min−1 with an increase in intensity, a respiratory exchange ratio >1.1 or greater, a maximal HR within 10 b·min−1 of predicted maximal HR, a blood lactate concentration ≥8 mmol·L−1, and an RPE of 18 or greater (17). Maximal HR was determined using the equation: 220-Age (23). At least 3 of the 5 criteria were met for all subjects and enabled researchers to record the V̇o2max as the highest 30 seconds V̇o2 measurement before volitional exhaustion and stoppage of the GXT occurred (20).

Ventilatory threshold was determined after the GXT through the pattern recognition method as described in previous research (29). This method was accomplished by confirming several identifiers. The first identifier was observed where the workload or time point when forced expired oxygen values increased after a plateau period. Second, the forced expired oxygen increase was aligned with the workload when the ratio of VE/V̇o2 increased without a subsequent increase in VE over ventilated carbon dioxide (VE/V̇co2) (5). A drastic increase in VE was also used to confirm that this workload was a true VT. Respiratory compensation point was determined as the second increase in VE and rise VE/V̇o2 without an increase in VE/V̇co2 (29). One experienced researcher determined VT and RCP, and both were confirmed by another blinded, experienced researcher.

The TT took place on an outdoor standardized 400 m running track at least 24 but no more than 48 hours after the GXT. Subjects were given 10 minutes to perform a warm-up and then were instructed to complete the 5,000 m distance in the fastest time possible. Times were recorded with a standard stopwatch (Accusplit AX602M500; West Warwick, RI, USA). The RPE for a subject's whole, upper, and lower body was recorded immediately after the finish of the TT. A finger-prick blood sample was taken 5 minutes after the subject completed the TT, and procedures were identical to blood lactate sampling as described after the GXT.

After another 24 to 48–hour period, subjects were then randomly assigned to either ET or RT and provided all needed equipment, including a HR watch (Garmin Forerunner 310XT; Olathe, KS, USA), chest strap, and charger (Garmin). An EBIKE (ElliptiGO Inc., Solana Beach, CA, USA) was loaned to each subject for the ET period. A bicycle helmet was loaned to the subject, if needed. A training notebook was also provided which included all subjective measurements and training schedules. Each training period included 20 prescribed exercise sessions between 30 and 60 minutes in duration. Exercise training sessions were 30, 40, 42, and 60 minutes in duration for easy, medium, hard, and long sessions, respectively. The exercise training zone prescriptions, easy (HR range = HR below VT), medium (HR range = HR above VT to HR at RCP), and hard (HR range = HR above RCP to HRmax), for both training groups were based on each subject's HR achieved at VT, RCP, and maximal effort time points during the V̇o2max test (10). Previous research (7) has shown HRmax to be similar between the treadmill and the elliptical. Prescribed percentages of exercise training in these zones were 80, 15, and 5% for easy, medium, and hard, respectively. These percentages reflect previously prescribed RT programs with the goal of improving physiological and performance variables measured in this study (10,32).

Easy training sessions included 30 minutes at an easy intensity. The medium training session included 10 minutes at an easy intensity for a warm-up, 20 minutes at a medium intensity, and then 10 minutes at an easy intensity for a cool down. The hard session involved similar warm-up and cool down to the medium session but included 1 minute hard intervals repeated 8 times with 2 minutes of easy intensity exercise in between intervals. The long training session entailed 50 minutes at an easy intensity with an additional 10 minute of medium intensity exercise to complete the session. Five training sessions were performed each week for the 4-week training period. All previously described exercise sessions were continuous and were performed once per week, except the easy sessions, which were completed twice per week.

A total of 7 testing sessions were completed by each subject for this study including a familiarization session preceding ET. During the familiarization session, each subject ensured he or she could safely and properly ride the EBIKE. Also at this time, handlebar height and stride length specifications were made to replicate the subject's preferred running position. Instructions were given to wear a helmet at all times while riding the EBIKE and to not cease leg movement at any time, while training. Subjects were also asked to refrain from any other exercise apart from the prescribed exercise program. Twenty-four to 48 hours after the completion of the final exercise session of the first 4-week training period, subjects returned to the laboratory for identical testing procedures to the initial session. Subjects were not required to complete additional HHQ and RHQ. A second training period, in a crossover design, was then completed. Subjects that first completed the ET now began the RT and vice versa. Twenty-four to 48 hours after the second training period, subjects concluded their participation by performing a third testing session, identical to the previous 2. Subjects were asked to be well hydrated and to not change their nutritional habits throughout the study and to consistently replicate their dietary intake before each testing session. Throughout the training period, subjects were contacted through email, telephone, or verbally to ensure adherence to the prescribed training program.

Statistical Analyses

A power analysis was conducted to calculate the proper sample size for this study using G*Power 3.1.2. Using a power of 0.80 and α of 0.05, with an effect size of 0.20, the required number of subjects was 12 for significance. Predictive Analysis Software (PASW Inc., Chicago, IL, USA) was used to analyze and report mean and SDs for each variable. A randomized, crossover design was chosen for this study. A 2 × 3 factorial repeated-measures analysis of variance (RM-ANOVA) was used to determine whether an order effect was present by comparing relative VT at 0-, 4-, and 8-week time points, regardless of training modality. An RM-ANOVA (within-ANOVA) test was used to compare V̇o2max, VT, RCP, RE, and TT times across the 3 testing time points: initial, post-EBIKE, and postrun. Percent change values were computed and paired t-tests were used to compare these values. The significance level was set at alpha α ≤ 0.05. A Fisher's least significance difference post hoc test was used to further analyze the significance between parametric variables (V̇o2max, VT, RCP, RE, and TT). A Bonferroni correction factor of p ≤ 0.0125 was used for paired t-test comparisons between ET and RT groups for the 4 HR intensities. Finally, training details, including exercise session frequency, duration, intensity, and total time, were compared between training modalities using paired t-tests.

Results

The 2 (mode) × 3 (time) factorial RM-ANOVA performed to assess an order effect did not demonstrate a significant interaction (p = 0.458) or main effect (p = 0.435) for relative VT. However, there was a significant main effect for time (p = 0.034). A post hoc analysis showed a significant difference between the initial time point and 4 weeks of training (p = 0.025), and the initial time point and 8 weeks of training (p = 0.034), regardless of what training modality was performed first. Because no order effect was determined, analyses proceeded without concern for which training modality was performed first. An RM-ANOVA was performed for all the descriptive variables (age, resting HR, resting BP, height, weight, BMI, and BF%). There were no significant differences (p > 0.05) for any of these variables over time. Paired t-tests were used to determine whether the total training time or total number of training sessions differed between ET and RT. The average total time per session was not significantly different (41:03 minutes for ET vs. 41:33 minutes for RT, p = 0.658), and the average number of training sessions was not significantly different (19.92 vs. 19.50, respectively, p = 0.210).

Table 2 displays the physiological and performance variables at each time point. An RM-ANOVA displayed no statistically significant differences among time points for all physiological and performance variables (V̇o2max, VT, RCP, RE, and TT times) except relative (p = 0.024) and absolute (p = 0.010) VT. A post hoc analysis revealed a significant difference between the relative VT values at the initial 40.17 ± 6.47 and post-ET 42.33 ± 6.96 (p = 0.024) and between the initial and postrun 41.60 ± 6.15 (p = 0.035) time points, but no significant difference between the modalities (p > 0.05). This was also seen for absolute VT values between the initial 2.54 ± 0.78 and post-EBIKE 2.68 ± 0.78 (p = 0.020) and initial and postrun 2.66 ± 0.80 (p = 0.009).

Table 2.
Table 2.:
Physiological and performance variables at initial, post-ET, and post-RT testing (mean ± SD).*†

The percent change between initial testing and each training modality was also evaluated using paired t-tests to better examine the degree of change in V̇o2max, VT, RCP, RE, and TT times. The only significant differences found were between the percent change values for RE and also TT times. Running economy improved by a significant amount postrun (-1.87 ± 5.06%) as compared with post-EBIKE (0.86 ± 3.58%) (p = 0.027). Also, TT times significantly improved postrun (-2.67 ± 2.95%) as compared with post-EBIKE (−0.04 ± 4.31%) (p = 0.022).

A 2 × 4 factorial RM-ANOVA was performed to determine whether average maximal HRs for easy, medium, hard, and long intensity sessions differed between training modalities. Actual maximal intensities did display a significant interaction (p = 0.015) between ET and RT groups and a significant main effect (p = 0.001) among exercise intensities. A Bonferroni correction factor of p ≤ 0.0125 was calculated for paired t-test comparisons between ET and RT groups for the 4 exercise intensities. For actual maximal HRs, only the easy intensity session was significantly different (p = 0.011) between modalities with the ET averaging 162.35 ± 12.30 b·min−1 and the RT averaging 168.07 ± 10.29 b·min−1.

Discussion

This study investigated the physiological responses to a 4-week training program using an EBIKE compared with a matched RT program in experienced runners. Inherent in the study design was analyzing the effectiveness of the EBIKE to maintain or improve cardiorespiratory fitness in experienced runners. Four weeks is a period that has been seen to produce short-term detraining effects and has been used in previous cross-training research (4,26). An analysis of measured physiological variables at 0, 4, and 8 weeks showed that there was no order effect seen in this randomized, crossover design study.

The results of this study support the hypothesis that there are no significant differences between ET and RT for V̇o2max, VT, RCP, RE, and TT over a 4-week training period in experienced runners. Results indicate that both training modalities were effective in increasing VT and maintaining all other physiological and performance variables when compared with initial values. This was expected because researchers designed the training program to increase these physiological and performance variables in experienced runners over a 4-week training period based on previous research (25). The prescribed training intensities included 80% below VT levels, 15% of exercise within a range between VT and RCP, and 5% high-intensity exercise above RCP. This training is representative of the exercise training an experienced endurance runner participates in (10,32). This result was not hypothesized but demonstrates that the novel EBIKE is an effective means for increasing VT with this training program.

These outcomes agree with previous research that have used similar training protocols to elicit physiological changes (25,32) with elliptical exercise. This was also observed in a study researching the effects of a 3-week elliptical training period on recently trained runners (18). However, subjects were only recently trained runners with an experience level of 4 weeks. In contrast, this study used experienced runners with an average of 9.25 ± 4.53 years running experience. Egaña and Donne (9) observed maintenance of V̇o2max and maximal VE using an elliptical trainer. In that study, only moderately trained nonrunners were used, and testing was performed on a cycle ergometer and not on a treadmill. In this study, a treadmill was used for GXTs and runners had an average V̇o2max of 57.92 ± 9.68 ml·kg−1·min−1 similar to previous research with experienced runners (1,38).

Beyond V̇o2max, no significant differences were observed for RE among the initial, post-EBIKE, or postrun time points at speeds of 2.68 and 3.13 m·s−1. A possible trend (p = 0.063, η2 = 0.222) was proposed for RE in that RE displayed a slight improvement, or lower V̇o2 value, at 3.13 m·s−1 after the RT period and only maintenance of RE after the ET period. Running economy has been found to be highly dependent on the neuromuscular capacity of a runner (27). This neuromuscular component of RE has been related to the ability to produce force or impact into the ground to propel oneself upward and forward. The EBIKE might be limited in this capacity because of the nonimpact, closed chain design that elliptical and EBIKE machines have compared with running. It is suggested that this difference in impact between elliptical exercise and running produces differences in muscular work required for riding the EBIKE and running (11). More research is needed to fully gauge the physiological efficacy of the EBIKE over longer periods compared with other cross-training modalities. In addition, the length of 4 weeks might not have been long enough to see significant decreases in measured variables in some subjects.

The average TT time was 1,303.00 ± 210.05 seconds, 1,303.17 ± 224.13 seconds, and 1,269.00 ± 188.62 seconds at the initial, post-ET, and post-RT time points, respectively. Researchers noted a possible practical improvement (p = 0.051, η2 = 0.237) in TT times after 4 weeks of RT. On average, runners were 34 seconds faster after RT. It is suggested that this improved performance is linked to the difference observed in impact forces during RT through improvements in RE. Subjects might have also been able to pace themselves during the TT having had knowledge throughout the RT period of their training paces and running distances.

Research investigating the stationary elliptical trainer has provided similar results. Over a 5-week period of elliptical training, trained high school runners were unable to maintain 3,000 m run performance when compared with RT (16). The elliptical trainer group became on average 47.70 ± 11.30 seconds slower and the run group became 9.40 ± 8.30 seconds faster. Honea (16) did not see any differences in V̇o2max, similar to this study, or VT. The ET in this EBIKE study did not show the TT performance decrement seen by Honea after elliptical training, and that may be due to the differences in design between the EBIKE and the elliptical. The elliptical trainer has been seen to produce vertical pedal reaction forces similar to walking, below 100% body weight (6), and lower average percentage body weight values compared with running (19). This further suggests a difference in neuromuscular and muscular work between running and nonimpact elliptical motion exercise. It is postulated that the EBIKE could allow for an increased training volume without an increase in injury risk due to its nonimpact nature. Future studies should investigate increased training volume using an EBIKE, separate or with RT.

In this study, the changes in 5,000 m TT performance from initial testing were similar between EBIKE and RT. However, Honea (16) showed decrements in 3,000 m TT performance after stationary elliptical training compared with running in trained high school cross country runners. In both this study and the study of Honea (16), easy, medium, and hard intensity sessions with similar number of sessions per week (i.e., 5–6) and similar ranges of session duration (i.e., 30–70 minutes) were used. The findings from both studies suggest that the EBIKE might be better at maintaining endurance running performance compared with stationary elliptical training in experienced runners.

Possible reasons for these improvements could be related to the running-similar recovery foot motion, lack of a fly wheel, and increased instability when riding the EBIKE compared with a stationary elliptical. The need to balance the EBIKE while riding may lead to increased recruitment of stabilizer muscles as compared with the stationary elliptical. The necessity to support one's weight, balance, and steer the EBIKE over ground, while in motion, could produce increased physiological demand as compared with running at a similar intensity. More research is needed to determine the impact of instability on the metabolic demands when riding the EBIKE. Additional research should also investigate important physiological, performance, and subjective variables such as RE, 5,000 m performance, and muscle soreness in the weeks after a period of ET when RT is reintroduced into one's training program to examine the effects of ET during the “return to run” training period. In summary, ET was not significantly different than RT for V̇o2max, RCP, RE, and TT times after 4 weeks of matched exercise training. An increase in VT was observed after either training period. Despite these findings, there were practical differences in the TT times and RE between training modalities.

Practical Applications

The results of this study suggest the use of the EBIKE as an effective cross-training method for experienced runners to maintain aerobic fitness and 5,000 m performance over a 4-week period. Elliptical bicycle–only training yielded similar physiological and performance maintenance or improvements compared with run-only training. The EBIKE not only is a nonimpact modality but also is a training modality that can elicit similar physiological and performance improvements to RT. This has special implication for coaches and clinicians aiming to improve physiological and performance variables in experienced runners without incurring an injury, in injured runners going through an injury recovery period, and the running population at large. Healthy runners wishing to recover from high impact RT could use the EBIKE to maintain or possibly improve fitness during cross-training periods.

Acknowledgments

The authors have a professional relationship with ElliptiGO Inc. No relationship was established before the agreement to conduct this research study. Authors received grant support from the College of Health Sciences and Professions Student Research Grant. Funding was also received from ElliptiGO Inc. The results of this study do not constitute endorsement of the product by the authors of the National Strength and Conditioning Association.

Funded by ElliptiGO Inc. Ohio University College of Health Sciences and Professions Student Research Grant.

References

1. Bickman D, Bentley D. The effects of short-term sprint training on MCT expression in moderately endurance-trained runners. Eur J Appl Physiol 96: 636–643, 2006.
2. Borg G, Noble B. Perceived exertion. Exerc Sport Sci Rev 2: 131–151, 1974.
3. Burnfield J, Shu Y, Buster T, Taylor A. Similarity of joint kinematics and muscle demands between elliptical training and walking: Implications for practice. J Amer Phys Ther Assoc 90: 289–305, 2009.
4. Bushman B, Andres F, Flynn M, Taylor M, Lambert C, Braun W, Fredrick F. Effect of four weeks of deep water run training on running performance. Med Sci Sports Exerc 29: 694–699, 1997.
5. Caiozzo V, Davis J, Ellis J, Azus J, Vandagriff R, Prietto C, McMaster W. A comparison of gas exchange indices used to detect the anaerobic threshold. J Appl Physiol Respir Environ Exerc Physiol 53: 1184–1189, 1982.
6. Chien H, Tsai T, Lu T. The effects of pedal rates on pedal reaction forces during elliptical exercise. Biomed Eng 19: 207–214, 2007.
7. Dalleck LC, Kravitz L, Robergs RA. Maximal exercise testing using the elliptical cross-trainer and treadmill. J Exerc Physiol Online 7: 94–101, 2004.
8. Dowzer CN, Reilly T, Cable NT, Nevill A. Maximal physiological responses to deep and shallow water running. Ergonomics 42: 275–281, 1999.
9. Egaña M, Donne B. Physiological changes following a 12 week gym based stair-climbing, elliptical trainer and treadmill running programs in females. J Sports Med Phys Fitness 44: 141–146, 2004.
10. Esteve-Lanao J, San Juan AF, Earnest CP, Foster C, Lucia A. How do endurance runners actually train? Relationship with competition performance. Med Sci Sports Exerc 37: 496–504, 2005.
11. Eston R, Mickleborough J, Baltzopoulus V. Eccentric activation and muscle damage: Biomechanical and physiological considerations during downhill running. Br J Sports Med 29: 89–94, 1995.
12. Frangolias DD, Rhodes EC. Maximal and ventilatory threshold responses to treadmill and water immersion running. Med Sci Sports Exerc 27: 1007–1013, 1995.
13. Hreljac A. Impact and overuse injuries in runners. Med Sci Sports Exerc 36: 845–849, 2004.
14. Hreljac A, Marshall RN, Hume PA. Evaluation of lower extremity overuse injury potential in runners. Med Sci Sports Exerc 32: 1635–1641, 2000.
15. Hoffmann JJ, Loy SF, Shapiro BI, Holland GJ, Vincent WJ, Shaw S, Thompson DL. Specificity effects of run versus cycle training on ventilatory threshold. Eur J Appl Physiol Occup Physiol 67: 43–47, 1993.
16. Honea DM. The impact of replacing run training with cross-training on performance of trained runners. In: Unpublished Master's Thesis. Boone, NC: Appalachian State University, 2012.
17. Howley E, Bassett D, Welch H. Criteria for maximal oxygen uptake: Review and commentary. Med Sci Sports Exerc 27: 1292–1301, 1995.
18. Joubert DP, Oden GL, Estes BC. The effects of elliptical cross-training on VO2max in recently trained runners. Int J Exerc Sci 4: 4–12, 2011.
19. Kaplan Y, Barak Y, Palmonovich E, Nyska M, Witvrouw E. Referent body weight values in over ground walking, over ground jogging, treadmill jogging, and elliptical exercise. Gait Posture 39: 558–562, 2014.
20. Loprinzi P, Cardinal B, Karp J, Brodowicz G. Group training in adolescent runners: Influence on VO2max and 5-km race performance. J Strength Cond Res 25: 2696–2703, 2011.
21. Lysholm J, Wiklander J. Injuries in runners. Am J Sports Med 15: 168–171, 1987.
22. Masumoto K, Horsch SE, Agnelli C, McClellan J, Mercer JA. Muscle activity during running in water and on dry land: Matched physiology. Inter J Sports Med 35: 62–68, 2014.
23. Mesquita A, Trabulo M, Mendes M, Viana JF, Seabra-Gomes R. The maximum heart rate in the exercise test: The 220-age formula or Sheffield's table? Portuguese J Cardio 15: 139–144, 1996.
24. Midgley A, McNaughton L, Jones A. Training to enhance the physiological determinants of long-distance running performance. Sports Med 37: 857–880, 2007.
25. Moxnes JF. Comparing VO2max improvement in five training methods. Adv Stud Theor Phys 6: 931–957, 2012.
26. Mujika I, Padilla S. Detraining: Loss of training-induced physiological and performance adaptations. Part I: Short term insufficient training stimulus. Sports Med 30: 79–87, 2000.
27. Nummela AT, Paavolainen LM, Sharwood KA, Lambert MI, Noakes TD, Rusko HK. Neuromuscular factors determining 5 km running performance and running economy in well-trained athletes. Eur J Appl Physiol 97: 1–8, 2006.
28. Outdoor Elliptical Bikes-ELLIPTIGO. 2014. Available at: http://www.elliptigo.com/. Accessed March 28, 2015.
29. Rabadán M, Díaz V, Calderon J, Benito P, Peinado A, Maffulli N. Physiological determinants of speciality of elite middle- and long-distance runners. J Sports Sci 29: 975–982, 2011.
30. Roche AF. Anthropometry and ultrasound. In: Roche A.F., Heymsfield S.B., Lohman T.G., eds. Human Body Composition. Champaign, IL: Human Kinetics, 1996.
31. Running USA. Welcome. Available at: http://www.runningusa.org/. Accessed March 28, 2015.
32. Seiler S, Jøranson K, Olesen BV, Hetlelid KJ. Adaptations to aerobic interval training: Interactive effects of exercise intensity and total work duration. Scand J Med Sci Sports 23: 74–83, 2013.
33. Svedenhag J, Seger J. Running on land and in water: Comparative exercise physiology. Med Sci Sports Exerc 24: 1155–1160, 1992.
34. Tanaka H. Effects of cross-training. Transfer of training effects on VO2max between cycling, running and swimming. Sports Med 18: 330–339, 1994.
35. Tenforde AS, Watanabe LM, Tamara MD, Moreno J, Fredericson M. Use of an antigravity treadmill for rehabilitation of a pelvic stress injury. PM R 4: 629–631, 2012.
36. Thompson W. ACSM's Guidelines for Exercise Testing and Prescription (8th ed.). Philadelphia, PA: Lippincott Williams & Wilkins, 2010. pp. 155.
37. van Gent RN, Siem D, van Middelkoop M, van Os AG, Bierma-Zeinstra SMA, Koes BW. Incidence and determinants of lower extremity running injuries in long distance runners: A systematic review [Review]. Br J Sports Med 41: 469–480, 2007.
38. Wilber R, Moffatt R, Scott B, Lee D, Cucuzzo N. Influence of water run training on the maintenance of aerobic performance. Med Sci Sports Exerc 28: 1056–1062, 1996.
39. Wilder RP, Sethi S. Overuse injuries: Tendinopathies, stress fracture, compartment syndrome, and shin splints. Clin Sports Med 23: 55–81, 2004.
40. Withers RT, Sherman WM, Miller M, Costill DL. Specificity of the anaerobic threshold in endurance trained cyclists and runners. Euro J Appl Physiol 47: 93–104, 1981.
Keywords:

running; injury; cross-training; performance

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