Spinning, an indoor stationary cycling program, is a popular form of group exercise taught in health and fitness facilities worldwide (23). Spinning programs are usually 40- to 60-minute variable intensity workouts incorporating 3 body positions (POS): seated (SEAT), running (RUN), or standing climb (SC) (22,23). Each Spinning session is a self-regulated workout in which participants employ perceived exertion (RPE) guided by the instructors' cues. Exercise intensity is changed by adjusting pedaling cadence and flywheel resistance on the Spinning bicycle.
Despite its popularity within the fitness community, little research exists that quantifies cardiorespiratory or neuromuscular responses to Spinning (2,9,11,12,17); and we could find no controlled studies that examined these responses relative to POS and RPE patterns commonly used during Spinning; the 2 factors by which changes in intensity are controlled during a Spinning workout. In contrast, numerous studies have examined cardiorespiratory and neuromuscular responses among supine, seated, and standing positions in road cyclists with varying results (10,13,14,19,25,29,32,33). A study by Caria et al. (9) assessed metabolic and cardiovascular responses during a simulated 50-minute Spinning class. Performances were categorized by a broad range of responses, with more than 42% of their simulated workout incorporating heavy (>10 metabolic equivalents) or very heavy (>13 metabolic equivalents) exercise (9). Although the 50-minute workout was divided into 11 phases incorporating varying intensities and positions, cardiorespiratory and metabolic data for individual phases, specific body positions, or perceived exertion levels were not reported.
Target heart rates (HRs) and HR zones are methods commonly used to identify training intensities during Spinning (21). Although patterns of change in HR and oxygen consumption (
) exhibit a relatively linear relationship at moderate levels of cycling, this relationship diverges at heavy and near-maximal efforts. However, this relationship has been established during cycling using a constant body position, rather than the variations in POS inherent to Spinning classes (5,15,16,18,27,34).
POS and RPE may also alter lower-body neuromuscular activity. Changes in neuromuscular activity during alterations in intensity and POS have not been examined during Spinning as they have during road cycling (10,19). In road cycling, Li and Caldwell (19) and Duc et al. (10) reported higher magnitudes and durations of quadriceps muscle activity during standing vs. seated cycling at the same work rate. Increases were attributed to the lack of saddle support and forward shift of the body's center of mass (19,30), which are also experienced during standing postures in Spinning. Data quantifying the levels of activity due to the interactive effects of POS and RPE would be invaluable not only for the targeting of specific muscle groups but also for the optimizing interval through the integration of distinct into a work/recovery duty cycle.
Given the paucity of controlled studies examining cardiorespiratory and neuromuscular responses during Spinning, the purpose of this study was to examine the effects of 3 POS and 4 RPE levels on the cardiorespiratory response and normalized vastus lateralis (VL) electromyographic activity (NrmsEMGVL) during a series of Spinning workout trials. This information can be used to improve program design and cuing during Spinning classes.
Experimental Approach to the Problem
To examine the effects of 3 different body positions and 4 levels of perceived exertion during Spinning, a repeated-measures design was used where 11 participants completed 4 days of testing in the Laboratory of Neuromuscular Research and Active Aging after an 8-hour fast. Participants completed 3 randomly assigned Spinning conditions on each testing day, for a total of 12 Spinning conditions. Cardiorespiratory variables were continuously measured by a computerized gas analyzer and VL muscular activity was continuously measured by a wireless surface electromyography (EMG) unit.
Eleven recreational athletes (4 men, 7 women, height = 1.68 ± 0.09 m, mass = 65.79 ± 11.29 kg, age = 24.4 ± 6.4 years) with an average of 3.2 ± 2.2 years of Spinning experience were enrolled in this study. All participants had at least 6 months of Spinning experience and were participating in at least 1 class per week. Participants had no recent history of orthopedic injury or cardiovascular, neuromuscular, or pulmonary disease. This study was approved by the Human Subjects Institutional Review Board at the University of Miami (IRB# 20991032), and all volunteers provided written informed consent before participation in this study.
Participants completed 4 laboratory sessions. Subjects were required to refrain from any exercise for 24 hours before testing and a 48-hour recovery period was maintained between testing sessions. During session 1, participants were asked to configure their handlebar and saddle positions on the Spinning NXT cycle (Star Trac, Irvine, CA, USA) to match positions they would use in a Spinning class. The settings were recorded and replicated during subsequent testing sessions. Sessions were conducted in the morning after an 8-hour fast and used the same testing procedures. The laboratory temperature during all testing sessions was 25 ± 1° C.
Figure 1 illustrates the experimental protocol. During each session, participant rode using 3 of the 12 possible combinations; therefore, all combinations were randomly assigned across the 4-day testing period. Conditions varied based on POS (SEAT, RUN, and SC) and RPE using a modification of the Borg RPE scale (4). Because exercise intensity is commonly determined by participants' perceived exertion during Spinning, the RPE scale allowed us to quantify participants' effort as they adjusted resistance and pedaling cadence. Workload, resistance, and cadence data were not recorded to replicate a Spinning class, where efforts are subjectively determined and no external feedback is provided. To further reflect class conditions, the Borg RPE scale was collapsed into 4 intensity levels: very low (RPE 6–9), low-medium (RPE 10–13), medium-high (RPE 14–16), and high (RPE 17–20). Consequently, the 12 randomly assigned conditions were SEAT/RPE 6–9, SEAT/RPE 10–13, SEAT/RPE 14–16, SEAT/RPE 17–20, RUN/RPE 6–9, RUN/RPE 10–13, RUN/RPE 14–16, RUN/RPE 17–20, SC/RPE 6–9, SC/RPE 10–13, SC/RPE 14–16, and SC/RPE 17–20.
For every session, EMG electrodes were positioned in a bipolar configuration proximal to the motor point of the right VL, a routine marker of quadriceps activity during cycling (3,8,19). Participants then performed a maximal voluntary isometric leg extension (MVICLE) allowing normalization of EMG data. After the MVICLE, the participant was fitted with a full face mask allowing continuous breath-by-breath gas exchange collection. Then, baseline data were collected as participants lay in a dimly lit, quiet room for 30 minutes. Participants were then tested under the first of 3 randomly assigned conditions for that day. Figures 2A–C illustrate the 3 test POS. Before each ride, participants performed a 5-minute warm-up in the SEAT position with no resistance at 60 revolutions per minute. Then, participants completed one of 12 randomly-assigned conditions for 3 minutes. Although a 3-minute bout may not be sufficient for an individual to reach steady state, this time interval mirrors the typical interval during Spinning class (20). Because accurate computation of metabolic cost requires steady state, computing energy expenditure was not feasible during testing. After each condition, a 1-minute cool down was performed in SEAT with no resistance.
Participants completed 3 rides per session. Electromyography and respiratory data were collected continuously during each ride. After ride 1, participants performed the next 2 randomly selected conditions each after a 15-minute rest. Testing sessions were separated by at least 24 hours.
Respiratory Gas Measurements
Respiratory gases were collected using a portable ergospirometry device (Oxycon Mobile, Hoechberg, Germany) (28). Before data collection, the participant was fitted with a mask that covered both the nose and the mouth. Breath-by-breath data included respiratory rate (RR; breaths per minute), pulmonary ventilation (VE; L·min−1), oxygen uptake relative to body weight (
; ml·kg−1·min−1), expired carbon dioxide relative to body weight (
; ml·kg−1·min−1), and respiratory exchange ratio (RER). Breath-by-breath data were averaged every 5 seconds across baseline and each test condition. Heart rate was continuously measured using a Polar T31 Coded Transmitter (Polar Inc., Lake Success, NY, USA) and transmitted through short-range telemetry to the Oxycon Mobile receiver. Before each session, the system was calibrated per manufacturer's instruction against a certified gas mixture of 16% O2 and 4% CO2.
To assure accurate electrode placement on the right VL for each session, the area of highest probability for motor point location was determined using previously established anatomical landmarks (24). Using a low-voltage stimulator (Grass S88 Stimulator; Grass Medical Instruments, Quincy, MA, USA), 5-millisecond pulses at 5 pulses per seconds were then delivered at a progressively reduced voltage (starting between 40 and 60 V) until only 1 point on the VL elicited an response. This was considered the motor point for the VL. The skin proximal to the motor point and over the tibial tuberosity was shaved, abraded, and cleansed with alcohol to remove dead surface tissues and oils and reduce skin impedance. Disposable Ag/AgCl dual electrodes (Noraxon USA, Inc., Scottsdale, AZ, USA) were then positioned parallel with the underlying muscle fibers as determined by a line drawn from the muscle's origin to insertion. A reference electrode was placed on the ipsilateral tibial tuberosity. To reduce movement artifacts, the electrode wires were held against the skin using self-adherent wrap.
A Noraxon TeleMyo 900 telemetry system (Noraxon USA, Inc.) was used for data collection (gain: 2000, band width: 3–500 Hz, sampling speed: 1024 Hz). Data were digitized using a 16-bit A/D convertor (Noraxon USA, Inc.), and stored on a personal computer. Electromyography signals were analyzed using MyoResearch XP Version 1.07 Software (Noraxon USA, Inc.) and a custom-built LabView program. The NrmsEMGVL of each 3-minute condition was used to quantify VL activity.
The MVICLE targeting the right VL was performed on a Biodex System 2 dynamometer (Biodex Corp., Shirley, NY, USA) at 1.57 rad of flexion at the hip and knee. Compensatory movements were minimized using Velcro straps across the thigh, waist, and chest. The MVICLE lasted 5 seconds, and the rmsEMG during the middle 3 seconds was used to normalize EMG data on each day. The middle 3 seconds were used to reduce artifacts expected at the beginning and end of the MVIC.
Separate 3 (POS) × 4 (RPE) repeated-measures analysis of variance (ANOVA) were used to detect differences among conditions for each variable (HR, RR, VE,
, RER, and NrmsEMGVL). If Mauchly's Test of Sphericity was statistically significant (p ≤ 0.05), a Huyn-Feldt adjustment was used to correct for the violation of sphericity. When main effects for POS or RPE or significant POS × RPE interactions were detected, Bonferroni post hoc tests were used to determine the sources. Additionally, Pearson product-moment correlation coefficients were computed to assess the relationship between HR and
for all conditions. Statistical significance was set a priori at p ≤ 0.05. All analyses were performed using IBM SPSS Statistics Version 19.0 software (International Business Machines Corp., Armonk, New York, USA).
Repeated-measures ANOVA revealed significant differences due to POS in RR (F(2,20) = 18.80, p < 0.001, ηp2 = 0.65), VE (F(1.47,14.73) = 7.68, p = 0.008, ηp2 = 0.43),
(F(1.45,14.47) = 10.46, p = 0.003, ηp2 = 0.51), and
(F(2,20) = 6.17, p = 0.008, ηp2 = 0.38). Table 1 shows pairwise comparisons for these variables. RR was significantly greater for RUN than SEAT (Mdiff = 3.93, SE =0.76, p = 0.001) and SC (Mdiff = 1.86, SE =0.60, p = 0.033), and SC was greater than SEAT (Mdiff = 2.06, SE =0.55, p = 0.011). VE was significantly greater during RUN than SEAT (Mdiff = 8.93, SE = 2.96, p = 0.039), but no difference was detected between RUN and SC, or SEAT and SC.
for both RUN (Mdiff = 5.37, SE = 1.55, p = 0.018) and SC (Mdiff = 3.28, SE = 0.89, p = 0.012) were significantly higher than SEAT. Although a main effect for POS was detected for
, no pairwise differences reached significance.
Significant differences were detected across RPE for RR (F(1.31,13.14) = 26.07, p < 0.001, ηp2 = 0.72), VE (F(1.95,19.48) = 43.44, p < 0.001, ηp2 = 0.81),
(F(1.66,16.60) = 40.33, p < 0.001, ηp2 = 0.81),
(F(1.64,16.36) = 54.45, p < 0.001, ηp2 = 0.85), and RER (F(2.29,22.90) = 30.80, p < 0.001, ηp2 = 0.76). Rating of perceived exertion pairwise comparisons are presented in Table 2. VE (Mdiff = 8.65, SE = 1.56, p = 0.001),
(Mdiff = 6.32, SE = 0.79, p < 0.001), and
(Mdiff = 4.54, SE = 0.51, p < 0.001) were higher at RPE 10–13 than RPE 6–9. Rating of perceived exertion 14–16 and RPE 17–20 produced higher responses in all variables compared with RPE 6–9 or RPE 10–13. Rating of perceived exertion 17–20 differed from RPE 14–16 for RR (Mdiff = 3.65, SE = 1.0, p = 0.026) and RER (Mdiff = 0.07, SE = 0.02, p = 0.049) with no differences in VE,
Significant main effects for POS (F(2,16) = 14.85, p < 0.001, ηp2 = 0.65) and RPE (F(3,24) = 61.98, p < 0.001, ηp2 = 0.89), and a significant interaction (F(6,48) = 2.71, p = 0.024, ηp2 = 0.25) were detected for HR. Post hoc tests indicated differences by POS at RPE 6–9 (F(16,2) = 15.84, p < 0.001) with RUN (Mdiff = 27.63, SE = 6.22, p = 0.006) and SC (Mdiff = 18.78, SE = 0.019, p = 0.019) producing greater HR than SEAT, and at RPE 17–20 (F(16,2) = 14.82, p < 0.001) with RUN (Mdiff = 11.90, SE = 2.73, p = 0.007) and SC (Mdiff = 8.86, SE = 2.14, p = 0.01) producing higher HR than SEAT (Figure 3).
Analysis of NrmsEMGVL indicated a significant main effect for RPE (F(3,24) = 41.12, p < 0.001, ηp2 = 0.84) and POS × RPE (F(6,48) = 2.52, p = 0.034, ηp2 = 0.24). Tests of simple effects indicated the sole difference by POS was found at RPE 6–9 (F(2,16) = 7.86, p = 0.004) with RUN producing greater NrmsEMGVL than SEAT (Mdiff = 0.14, SE = 0.45, p = 0.04; Figure 3).
Pearson product-moment correlation coefficients showed significant positive correlations between HR and
for all POS at RPE 6–9 and RPE 10–13. At RPE 6–9, the highest correlation was during SEAT (r = 0.861, p = 0.001), with RUN (r = 0.665, p = 0.026) and SC (r = 0.723, p = 0.012) showing significant, albeit lower, correlations. At RPE 10–13, SEAT (r = 0.635, p = 0.036), RUN (r = 0.764, p = 0.010), and SC (r = 0.645, p = 0.032) also produced positive correlations. At RPE 14–16, SEAT produced a significant positive correlation (r = 0.758, p = 0.007), whereas RUN (r = 0.525, p = 0.119) and SC (r = 0.157, p = 0.664) failed to reach significance. At RPE 17–20, correlations for SEAT (r = 0.534, p = 0.091), RUN (r = 0.389, p = 0.237), and SC (r = 0.307, p = 0.359) were not significant.
The findings of this study have practical implications for program design and cuing during Spinning classes. When considering POS, the fact that both RUN and SC produced higher
and RR responses than SEAT indicates that both positions should be emphasized over SEAT when goals are to elicit improvements in aerobic capacity. The higher
and RR for the 2 standing positions vs. SEAT may be attributable to increased utilization of upper-body musculature and the need for riders to support their body weight, which is not supported by the saddle.
A number of authors reported higher
, RR, and VE in standing compared with seated positions on road bicycles (13,14,25,29,33). Tanaka et al. (33) reported increased
during a standing vs. seated position when cyclists rode on a treadmill at 4% grade and 20 km·h−1. Unlike our study, the
responses reported by these researchers were dependent on the applied workload with no differences seen between the 2 body positions at an increased grade and reduced cycling speed (10% grade at 12.3 km·h−1). Comparisons between these studies are difficult since our riders' efforts were based on perceived exertions, whereas workloads during their study were dictated by grade and speed. Comparisons are further complicated since treadmill cyclists reported lower RPE for standing vs. seated positions at 10% grade. The reported decrease in RPE during treadmill cycling related to grade, vs. Spinning based on RPE, is not unexpected given that coordination between arms and legs as the bike is shifted from side to side during standing provides a mechanical advantage during cycling not possible during Spinning (29,31).
Overall, the 2 standing positions in Spinning are categorized by greater ventilatory responses than the seated position. The higher RR during RUN and SC, and VE during RUN, compared with SEAT in our study reflect results reported by Millet et al. (25) and Harnish et al. (14) in road cycling. Millet et al. (25) reported significant increases in both RR and VE when cycling uphill on a constant 5.3% gradient at 75% of the individual's peak power output in a standing position as compared with a seated position. The results reported by Millet et al. are supported by Harnish et al. (14) who also found significant increases in VE and RR when standing cycling compared with seated cycling uphill on a 5% grade at varying intensities (50, 65, and 75% of peak power output). Once again, direct comparisons may not be relevant to this study due to wind resistance, lateral movements of the bicycle, and other factors not experienced on a stationary bicycle in a laboratory setting.
When considering the effects of RPE on cardiorespiratory responses, we found that as RPE increased from RPE 6–9 through RPE 14–16, significant increases occurred in VE,
; however, no further increases occurred at RPE 17–20. Because these results were independent of POS, they can have considerable impact on workout design and cuing. They indicate that Spinning participants need not work at extremely high RPE to maximize cardiorespiratory responses. Results for RPE 6–9 through RPE 14–16 mirror those by Perez-Landaluce et al. (26), who noted that RPE is a practical method of prescribing exercise intensities in road cyclists, showing strong linear correlations between RPE and
. Additionally, Kang et al. (17) showed that at a constant workload of 67 ± 3% HRmax or varying intensities where workload averaged 68 ± 4% HRmax, average RPE reflected the average intensity. This is especially pertinent since their measurements were made within the intensity range of a typical Spinning class (2).
In our study, HR at both a very low intensity (RPE 6–9) and a high intensity (RPE 17–20) in SEAT were lower than HR during RUN or SC; however, there were no differences among POS for RPE 10–13 or RPE 14–16. Similar to our findings at RPE 17–20, Ryschon and Stray-Gundersen (29) reported significant
and HR increases during standing vs. seated treadmill cycling at a 4% grade at an intensity mirroring RPE 17–20, reflecting our results. Additionally, at a similar work intensity and 4% grade, Tanaka et al. (33) reported a significantly higher HR and
for treadmill cycling in a standing compared with seated position; however, this difference dissipated at a 10% grade.
Heart rate displayed a significant POS × RPE interaction, indicating nonuniform trends in data. Although increases in HR are well documented as an individual changes posture from supine to upright, we are unable to definitively explain why HR in SEAT at RPE 10–13 and RPE 14–16 was not significantly different from standing Spinning positions. Previous research suggests that during lower-intensity Spinning, participants may report RPE lower than their measured physiological responses (17). This inaccurate reporting may explain the HR differences seen among POS at higher vs. lower RPE, with participants reporting RPE below physiological response for SEAT. Existing data examining seated and standing positions in road cyclists at varying intensities are also inconsistent (14,25). Harnish et al. (14) and Swain and Wilcox (32) found no differences in
or HR between seated and standing uphill cycling at RPE between 9.3 and 15.1 for outdoor and treadmill environments, respectively. However, Millet et al. (25) reported significantly higher HR and VE during standing vs. seated cycling at 5.3% grade (RPE 9.9–11.1), but no difference in
. Once again equipment and environmental differences affect the efficacy of these comparisons.
Pearson product-moment correlation coefficients indicate
and HR are linearly correlated at RPE 6–9 and RPE 10–13, but not higher RPE. The linear relationship between HR and
has been repeatedly demonstrated at lower intensities and exhibits an increasing level of nonlinearity as levels of exertion increase (5,15,16,34). Greater variability in the HR-
relationship at high vs. low intensities may help explain the differing HR responses seen due to POS at different intensities in our study.
Our results reveal that at low intensities (RPE 6–9) for SEAT, NrmsEMGVL was significantly lower than RUN, but no differences were observed between SEAT and SC. Alterations in firing patterns are seen with changes in pedaling kinetics and kinematics when transitioning from a seated to standing position during road cycling (10,19). These changes are related to removal of saddle support, which creates a forward shift in body center of mass and altered hip and knee reaction forces (1,7,19,30,31). Additionally, load redistribution from 3 points of support while seated (saddle, handlebars, and pedals) to 2 points of support while in the 2 standing positions (handlebars and pedals) is evident (31). During RUN, the majority of participants' weight is commonly centered over the pedals with hands resting lightly on the handlebars, whereas in SC, weight is more evenly distributed between these structures (22). This help explains the differences in NrmsEMGVL between RUN and SEAT, but not SC and SEAT at RPE 6–9. Our results showed no differences in NrmsEMGVL due to POS at RPE above 9. Similarly, Li and Caldwell (19) reported that at a moderate power output, no difference in VL activity was detected because of posture; however, they did note a trend for a greater duration of muscle activity across the pedal stroke. Timing and burst duration of muscle activity of the VL was not investigated in this study; however, if included in future studies, it may provide further insights into the bases for the muscle activation patterns seen during Spinning.
Duc et al. (10) and Li and Caldwell (19) reported significant increases in mean EMG of the gluteus maximus (GM), vastus medialis (VM), rectus femoris (RF), biceps femoris (BF), and tibialis anterior for standing vs. seated riding. Duc et al. (10) did not test the VL, and Li and Caldwell (19) reported no difference in VL activity between conditions. Caldwell et al. (6) showed that during standing, knee extensor moments are prolonged, causing greater activation the VM and RF. Because the VL, VM, and RF are all knee extensors, they show similar activity under many conditions; however, in RUN and SC vs. SEAT, there is greater forward hip translation compared with knee translation resulting in smaller knee excursion levels (19) and higher EMG in the muscles crossing the hip joint (GM, RF, and BF) (10,19). We observed a difference in NrmsEMGVL between SEAT and RUN only at a low intensity, consistent with results reported by Li and Caldwell (19).
A limitation of the study was the use of a 3-minute bout which, while it reflects an interval duration typically used in a Spinning class, does not allow an examination of the changes that might occur in muscle utilization patterns and respiratory variables due to fatigue in a typical 60-minute class.
Our results indicate that increased cardiorespiratory responses, which may improve cardiovascular fitness and increase caloric output, can best be attained during Spinning by emphasizing the RUN and SC positions. Additionally, individuals need not work at near-maximal RPE to attain maximal cardiovascular benefits, as there was no difference between RPE 14–6 and RPE 17–20. Heart rate is not consistent across position or perceived exertion and seems to be a poor marker of oxygen consumption, especially at high RPE, indicating that HR may be ineffective for assessing cardiorespiratory responses during Spinning. Finally, when targeting muscle activation, POS during Spinning does not affect NrmsEMGVL at low-medium, medium-high, and high RPE. These findings will allow the Spinning instructor to design exacting intervals, which can address the targeted goals of a specific class and will aid in the structuring of intervals that can maximize results throughout the warm-up, training, and cool-down segments of the class.
The authors thank Dr. Moataz Eltoukhy at the University of Miami for contributing to this research through assistance with electromyography analysis, our subjects for their cooperation and time during data collection, and the Patti and Allan Herbert Wellness Center for the use of the Spinning stationary cycle used in this study. This research was performed with no external financial support. The authors have no conflict of interest.
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