Several investigators have demonstrated that chronic eccentric leg cycling is an effective method for improving lower body neuromuscular function (e.g., quadriceps muscle size, strength, and mobility) in a variety of patient and athletic populations. To date, there are no reports of using eccentric arm cycling (ECarm) as an exercise modality, probably in large part because of the lack of commercially available ECarm ergometers.
Purpose: Our purposes for conducting this study were to 1) describe the design and construction of an ECarm ergometer and 2) compare ECarm to traditional concentric arm cycling (CCarm).
Methods: All of the parts of a Monark 891E cycle ergometer (Monark Exercise AB, Vansbro, Sweden) were removed, leaving the frame and flywheel. An electric motor (2.2 kW) was connected to the flywheel via a pulley and a belt. Motor speed and pedaling rate were controlled by a variable frequency drive. A power meter quantified power and pedaling rate, and provided feedback to the individual. Eight individuals performed 3-min ECarm and CCarm trials at 40, 80, and 120 W (60 rpm) while V˙O2 was measured.
Results: The ECarm ergometer was simple to use, was adjustable, provided feedback on power output to the user, and allowed for a range of eccentric powers. V˙O2 during ECarm was substantially lower compared with CCarm (P < 0.001). At similar V˙O2 (0.97 ± 0.18 vs 0.91 ± 0.09 L·min−1, for ECarm and CCarm, respectively, P = 0.26), power absorbed during ECarm was approximately threefold greater than that produced during CCarm (118 ± 1 vs 40 ± 1 W, P < 0.001).
Conclusion: This novel ECarm ergometer can be used to perform repetitive, high-force, multijoint, eccentric actions with the upper body at a low level of metabolic demand and may allow researchers and clinicians to use ECarm as a training and rehabilitation modality.
1Swedish Winter Sports Research Center, Department of Health Sciences, Mid Sweden University, Östersund, SWEDEN; 2Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT
Address for correspondence: Steven J. Elmer, Ph.D.,Department of Exercise and Sport Science, University of Utah, 250 S. 1850 E., Room 241, Salt Lake City, UT, 84112; E-mail: email@example.com.
Submitted for publication June 2012.
Accepted for publication July 2012.
Eccentric exercise training is often implemented during rehabilitation from injury and also during sport training. Several investigators have demonstrated that chronic eccentric leg cycling (6–12 wk) is a potent stimulus for improving neuromuscular function in the lower body (e.g., quadriceps muscle size, strength, and mobility) in a variety of populations including patients with Parkinson disease (3,4), cancer survivors (18), multiple sclerosis patients (16), individuals with total knee arthroplasty (19,24) or anterior cruciate ligament injuries (12–14), elderly individuals (17,27), healthy individuals (6,9,20–22), and athletes (15,23). Given the efficacy of eccentric leg cycling, it is possible that eccentric arm cycling (ECarm) might also serve as a useful multijoint model for delivering eccentric exercise interventions that target muscle and joint-specific impairments of the upper body. To the best of our knowledge, there are no previous reports documenting the development and use of ECarm.
The lack of commercially available eccentric arm cycle ergometers most likely precludes the use of ECarm as an exercise modality. In our laboratory, we have constructed an eccentric arm cycle ergometer using exercise equipment and commonly available parts, along with a modest amount of custom fabrication (Fig. 1). Our primary purposes for conducting this investigation were to describe the technical aspects of the eccentric arm cycle ergometer and to assess the device in terms of the following design criteria: 1) simplicity of use, 2) ability to accommodate both able-bodied individuals and individuals with disabilities, 3) capacity to provide both real-time and archived feedback on power output, and 4) capacity to allow for a broad range of eccentric powers. Our secondary purpose was to compare acute physiological responses to eccentric and traditional concentric arm cycling (CCarm). Based on previous reports comparing eccentric and concentric leg cycling (2,5,21,26), we hypothesized that ECarm would be performed at a lower metabolic demand compared with CCarm. We anticipate that this brief report will serve as a useful introduction for researchers and clinicians who want to use ECarm as a research model and/or as a training and rehabilitation modality.
In this section, we provide a description and illustration of the essential components of the eccentric arm cycle ergometer as well as information regarding calibration of the device. We also describe the experimental trials that were performed to compare physiological responses between ECarm and CCarm.
Ergometer frame and seat
We started with an existing Monark 891E cycle ergometer and adjustable stand (Monark Exercise AB, Vansbro, Sweden) that were designed for traditional CCarm. We removed all of the original parts (e.g., plastic side panels, computer controller, and cranks), leaving only the frame, flywheel, and stand (Fig. 1). This specific model of ergometer was not equipped with a seat system. Thus, we constructed a seat system (Fig. 1) that included two levels of adjustability (up/down and fore/aft) and attached this system to the ergometer. Collectively, the adjustable ergometer stand and seat system could accommodate a broad range of body sizes, as well as wheelchairs, when the seat system was removed. After these modifications had been made, the ergometer was equipped with a power measurement device (described in the latter part), standard ergometer chain, and handles designed for arm cycling. Finally, the ergometer was secured to the floor to minimize movement. Note that, although we chose to start with a commercially available arm cycle ergometer, one could also make similar modifications (as described previously) to an existing leg cycle ergometer with the additional requirement of constructing an adjustable stand or table to elevate the ergometer off the ground.
Motor and speed controller
The flywheel of the ergometer was driven in the reverse direction by a 2.2-kW, three-phase alternating current electric motor (BEVI 2SIE1004A; BEVI AB, Blomstermåla, Sweden; Fig. 2). Specifically, an industrial V belt was used to connect the motor’s pulley (diameter 63 mm) to an external pulley (diameter 180 mm) that was mounted on the flywheel. The tension in the V belt was adjusted using the sliding mount of the motor to the ergometer frame. Note that the gear ratio from the crank to the flywheel was 1:3.786. The motor was controlled using a variable frequency drive (Invertek Optidrive-E i55; Invertek Drives Ltd., Welshpool, Wales), which allowed for control of motor speed and pedaling rate (Fig. 2). With this configuration, the ergometer functioned in an isokinetic mode and thus the resistance (i.e., power absorption) was determined by the individual performing the exercise.
Power measurement device
The ergometer was equipped with a power meter (Schoberer Rad Messtechnik (SRM), Jülich, Germany; Fig. 2) to quantify power, work, and pedaling rate. This feedback system enabled the individual to resist the handles at a prescribed target power (e.g., 120 W). Data recorded with the SRM power meter can be downloaded to a computer and subsequently analyzed using programs such as SRM Training System, CyclingPeaks, and/or Microsoft Excel. Although the SRM power meter represents a significant cost, it provides accurate measurements of cycling power (1,11,25) and can be used on other laboratory ergometers and bicycles. Accordingly, it may be useful in a broad range of research, clinical, and sport applications.
Mechanical calibration of the eccentric arm cycle ergometer was achieved through a static calibration of the SRM power meter, which has been previously described by Wooles et al. (28). Briefly, the power meter and crank axle were secured in place with the crank arm oriented in the vertical position (0°). A spare section of bicycle chain was placed around the chainring, and a known mass (e.g., 100 kg) was suspended from one end of the chain. With the known mass and lever arm, the torque applied to the SRM power meter was calculated with the following equation:
where T is the torque (N·m), m is the mass of the object suspended (kg), g is the gravitational acceleration (m·s−2), and r is the radius of the chainring (m). The functional relation between the known torque applied and the frequency output (Hz) displayed on the SRM power control unit was used to calculate a calibration factor using the following equation:
where C is the calibration factor (Hz·N·m−1), floaded is the frequency output (Hz) displayed when a known mass is applied, and funloaded is the frequency output without an applied load (i.e., “zero offset”). Calibration trials were performed a total of three times with the crank oriented in four different positions (0°, 90°, 180°, and 270°). The mean of all calibration factors was entered into the SRM power control unit. After the calibration procedures were completed, the SRM power meter was attached to the ergometer frame. An funloaded value was obtained before all eccentric cycling trials because this value can vary slightly with changes in ambient temperature. According to the manufacture’s guidelines and previous reports (28), calibration of the SRM power meter should be performed once every 6 months because of drift in the calibration factor over time. Finally, an alterative procedure to the static calibration described previously would involve performing a dynamic calibration, which allows for measurement of the calibration factor while the SRM power meter is moving. However, a dynamic calibration system can be expensive, difficult to set up, and may have intrinsic errors (28).
Eight healthy individuals (age: 33 ± 5 yr; mass: 72 ± 7 kg; height: 1.74 ± 0.08 m) who engaged in a variety of different physical activities involving their upper body (e.g., cross-country skiing, kayaking, and strength training) volunteered to participate in this study. Experimental procedures used in this investigation were approved by the Umeå University Regional Ethical Review Board. The protocol and procedures were explained verbally, and all participants provided written informed consent before testing. Participants performed three practice trials of ECarm and CCarm before the experimental data collection to become familiar with the cycle ergometers and testing protocol.
During the experimental week, participants reported to the laboratory on two separate occasions to perform either ECarm or CCarm trials that were assigned in a random fashion. On each day, participants performed a CCarm warm-up for 3 min at 20 W. Subsequently, participants performed arm cycling trials for 3 min at 40, 80, and 120 W while oxygen consumption was measured. A recovery period of at least 3 min was provided between trials. For the ECarm trials, participants were instructed to resist the reverse moving handles of the eccentric arm cycle ergometer (isokinetic mode) at the specified target powers. Pedaling rate was set to 60 rpm, and the SRM power meter (sampled at 1 Hz) displayed the power that the participant was absorbing. During each trial, participants were given at least 30 s to stabilize at their target power and then maintained that target power for 3 min during which data were collected. For the CCarm trials, participants were instructed to cycle at 60 rpm while the ergometer (mechanically braked Monark 839E adapted for arm cycling, constant power mode) maintained the prescribed power. Note that the concentric arm cycle ergometer was also equipped with an SRM power meter (sampled at 1 Hz) that was calibrated as described previously. Thus, power was measured at the same location (i.e., power delivered to the ergometer crank) for both ergometers. Finally, participants were carefully placed on each ergometer such that the crank axle was set just below the level of the heart, and the elbow was positioned at a comfortable angle (approximately 20° ulnar notch to humoral head) when the cranks were horizontal.
Oxygen consumption (V˙O2) was measured with a mixed expired procedure using an ergospirometry system (AMIS 2001 model C; Innovision A/S, Odense, Denmark), equipped with an inspiratory flow meter. The gas analyzers were calibrated with a high-precision two-component gas mixture of 16.0% O2 and 4.5% CO2 (Air Liquide, Kungsängen, Sweden), and calibration of the flow meter was performed at low, medium, and high flow rates with a 3-L air syringe (Hans Rudolph, Kansas City, MO). Ambient conditions were monitored with an external apparatus (Vaisala PTU 200; Vaisala OY, Helsinki, Finland). Expired O2 was monitored continuously, and values were averaged over the final 30 s of each trial.
A repeated-measures ANOVA was used to assess differences in V˙O2 between eccentric and CCarm. Data are presented as mean ± SD, and alpha was set to 0.05.
The essential components of our eccentric arm cycle ergometer included the following: 1) ergometer frame and seat, 2) motor and speed controller that propelled the flywheel and cranks, and 3) power measurement device that provided feedback to the individual performing the exercise. The ergometer was easy to use, and calibration was achieved using basic tools and did not require specialized equipment. The adjustable seat enabled careful positioning of the participant and could be removed to accommodate a wheelchair. Furthermore, the SRM power meter served as a means to provide the participant with feedback relating to power, pedaling rate and total work and also allowed for data to be transferred to a computer.The ergometer also allowed for a range of eccentric power outputs. With these aspects in mind, the ergometer met each of the design criteria.
Mean powers absorbed during ECarm (40 ± 1, 80 ± 1, and 118 ± 1 W) and produced during CCarm (40 ± 1, 81 ± 4, and 121 ± 2 W) were very close to the prescribed powers of 40, 80, and 120 W. Repeated-measures ANOVA procedures revealed a significant effect of cycling mode on V˙O2 values (P < 0.001), indicating that ECarm was performed with lower levels of metabolic demand compared with CCarm (Fig. 3). At similar levels of V˙O2 (0.97 ± 0.18 vs 0.91 ± 0.09 L·min−1 for ECarm and CCarm, respectively, P = 0.28), power produced during ECarm was approximately threefold greater than the power produced during CCarm (118 ± 1 vs 40 ± 1 W, P < 0.001; Fig. 4).
We constructed an eccentric arm cycle ergometer using existing exercise equipment, readily available parts, along with a modest amount of custom modification. The eccentric arm cycle ergometer met each of the design criteria because it was simple to use, was adjustable, provided real-time and archived feedback on power output to the user, and allowed for a range of eccentric power outputs. Our experimental results demonstrated that ECarm was performed at a considerably lower level of metabolic demand compared with traditional CCarm, which extends the application of eccentric cycle ergometry from the lower body to the upper body. Together, these findings highlight the design, construction, and application of a novel eccentric cycle ergometer that can be potentially used for training muscles in the upper body.
Design considerations and safety issues
Based on our experiences using the ECarm ergometer, we have identified several important design and safety issues that are worth noting. One important issue to consider is that bottom bracket and handles can loosen during ECarm. This loosening occurs because the threading is oriented for CCarm so as to prevent loosening during exercise. Our alternative solution was to use industrial thread locking compound on the bottom bracket cups and the handles. Another issue to consider is the selection of handle. During prolonged ECarm trials (e.g., 20 min), we have found that some individuals describe hot spots in the hands and even experience mild blistering. This issue has been partially circumvented by having the individual wear gloves, and we are currently developing a handle with a larger surface area. We are also working to improve the safety features of the ergometer by installing an emergency off switch. In our current configuration, the on/off switch is on the motor controller and is accessible by the investigator who usually stands adjacent to the user.
ECarm can be potentially injurious. For example, performing this exercise in a position that allows the elbow to reach full extension could result in injuries to the elbow, shoulder, and/or spine because the handle could forcefully compress these joints. In addition, because ECarm is a repetitive, high-force, multijoint exercise, it could be possible to induce muscle damage and soreness in the upper body in a similar manner as previously reported with acute eccentric leg cycling (7–10). To avoid such injuries, we strongly advise that researchers and clinicians carefully select an appropriate seat position, give clear instructions, provide the user with several familiarization trials, and progressively increase the duration and intensity of the ECarm trials.
Experimental results from this investigation demonstrate that ECarm can be performed at a considerably lower metabolic demand compared with CCarm. Furthermore, when V˙O2 was similar between the two exercise modalities, power was almost three times greater during ECarm. Taken together, these results highlight the high-force, low-cost nature of eccentric muscle actions. These findings also support and extend upon previous comparisons (2,5,21,26) of the physiological responses associated with eccentric and concentric leg cycling. Interestingly, several previous authors (3,4,6,9,12–24,27) have demonstrated that 6–12 wk of eccentric cycling training (e.g., 10–30 min, three times a week) is an effective method for improving neuromuscular function in the lower body in a variety of populations. To date, there are no reports documenting the use of ECarm in rehabilitation or sport.
Traditionally, CCarm has served as an important exercise modality in rehabilitation. This type of exercise, however, requires substantial effort to produce modest powers and can be quite challenging for individuals who have a low tolerance for exercise and relatively untrained muscles in the upper body. Based on our initial results, along with the positive outcomes associated with chronic eccentric leg cycling (3,4,6,9,12–24,27), it is possible that ECarm training may be useful in targeting muscle and joint-specific impairments in the upper body particularly in individuals with limited central capacity (e.g., wheelchair-dependent individuals, frail elderly individuals, and persons with chronic obstructive pulmonary disease). Additionally, athletes who rely heavily on muscles in the upper body for locomotion and sport performance (e.g., cross-country skiing, swimming, kayaking, and rowing) may also find value in incorporating ECarm into their training programs.
This brief report describes the technical aspects of a novel eccentric arm cycle ergometer that can be used for training muscles in the upper body. The ergometer was simple to use, was adjustable, provided real-time and archived feedback on power output to the user, and allowed for a range of eccentric powers, thus meeting our design criteria. Furthermore, with this ergometer, participants were able to perform repetitive, high-force, multijoint, eccentric actions with the upper body at a considerably lower level of metabolic demand compared with traditional CCarm. Our findings have implications for those individuals who plan to use ECarm as an exercise modality and wish to construct their own ergometer.
This investigation was financially supported by the Swedish Sports Organization for the Disabled and the Swedish National Center of Research in Sports (CIF).
We sincerely thank Mikael Therell for his technical assistance with the construction of the ergometer. We also thank Stan Lindstedt and Paul LaStayo helpful discussions relating to ECarm. Finally, we could not have constructed this ergometer without the technical assistance from Mikael Therell.
The authors report no conflict of interest, and the results of the present investigation do not constitute endorsement by the American College of Sports Medicine.
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Keywords:©2013The American College of Sports Medicine
ECCENTRIC MUSCLE CONTRACTION; POWER; MULTIJOINT EXERCISE; REHABILITATION; ERGOMETRY