Cardiorespiratory Parameters Comparison Between Incremental Protocols Performed in Aquatic and Land Environments by Healthy Individuals: A Systematic Review and Meta-Analysis

BACKGROUND

Physical properties of water cause physiological changes in the immersed human body compared with the land environment. Understanding the magnitude of cardiorespiratory alterations might ensure adequate intensity control during aquatic exercise programs.

OBJECTIVE

We aimed to compare the oxygen uptake (VO₂), heart rate (HR), and rating of perceived exertion (RPE) parameters during aquatic and land incremental tests.

METHODS

Four databases (PubMed, LILACS, EMBASE, and SPORTDiscus) were searched in September 2020. Eligibility criteria included studies in a crossover design comparing aquatic and land incremental tests for healthy individuals with at least one of the following parameters: VO₂ (maximal, VO_2max; anaerobic threshold, VO_2AT), HR (HR_max; HR_AT), and RPE (RPE_max; RPE_AT). The random-effects meta-analysis included mean difference and 95% confidence interval for VO₂ and HR or standardized mean difference for RPE. The Joanna Briggs Institute Critical Appraisal tool was adapted to assess methodological quality.

RESULTS

Twenty-eight studies were eligible and included in the meta-analysis. Aquatic protocols showed lower values compared with land for VO_2max (- 7.07 mL.kg^-1.min^-1; - 8.43 to - 5.70; n = 502), VO_2AT (- 6.19 mL.kg^-1.min^-1; - 7.66 to - 4.73; n = 145), HR_max (- 11.71 bpm; - 13.84 to - 9.58; n = 503), and HR_AT (- 15.29 bpm; - 19.05 to - 11.53; n = 145). RPE_max (0.01; - 0.16 to 0.18; n = 299) and RPE_AT (- 0.67; - 1.35 to 0.02; n = 55) values were similar between aquatic and land protocols.

CONCLUSIONS

Our study reinforces the specificity of the environment during incremental tests for prescribing exercises based on physiological parameters as VO₂ and HR parameters presented lower values in aquatic protocols than land protocols. Conversely, RPE seems an interchangeable measure of exercise intensity, with similar values during the protocols in both environments. Substantial levels of heterogeneity were present for the VO_2max and HR_max meta-analyses, and as such, results should be interpreted with attention. PROTOCOL REGISTRATION: This study was registered in the International Prospective Register of Systematic Reviews (PROSPERO; CRD42020212508).

A Study on the Relationship between RPE and sEMG in Dynamic Contraction Based on the GPR Method

The rating of perceived exertion (RPE) and surface electromyography (sEMG) describe exercise intensity subjectively and objectively, while there has been a lack of research on the relationship between them during dynamic contractions to predict exercise intensity, comprehensively. The purpose of this study was to establish a model of the relationship between sEMG and RPE during dynamic exercises. Therefore, 20 healthy male subjects were organized to perform an incremental load test on a cycle ergometer, and the subjects’ RPEs (Borg Scale 6–20) were collected every minute. Additionally, the sEMGs of the subjects’ eight lower limb muscles were collected. The sEMG features based on time domain, frequency domain and time–frequency domain methods were extracted, and the relationship model was established using Gaussian process regression (GPR). The results show that the sEMG and RPE of the selected lower limb muscles are significantly correlated (p < 0.05) but that they have different monotonic correlation degrees. The model that was established with all three domain features displayed optimal performance and when the RPE was 13, the prediction error was the smallest. The study is significant for lower limb muscle training strategy and quantification of training intensity from both subjective and objective aspects, and lays a foundation for sEMG further applications in rehabilitation medicine and sports training.

Anaerobic Threshold in a Water-Based Exercise: Agreement Between Heart Rate Deflection Point and Lactate Threshold Methods

ABSTRACT

Alberton, CL, Andrade, LS, Pinheiro, RB, and Pinto, SS. Anaerobic threshold in a water-based exercise: agreement between heart rate deflection point and lactate threshold methods. J Strength Cond Res 35(9): 2472-2478, 2021-The purpose of this study was to compare and assess the agreement of the heart rate (HR) and rating of perceived exertion (RPE) corresponding to the anaerobic threshold (AT) between HR deflection point (HRDP) and lactate threshold (LT) methods during a water-based exercise in young men. Sixteen young men (24 ± 6 years) performed the experimental protocol, which comprised the performance of a maximal incremental test during the water-based stationary running exercise. The initial cadence corresponded to 90 b·min-1, with 10 b·min-1 increases every 3 minutes up to exhaustion. Heart rate was monitored every 30 seconds while blood lactate concentrations and RPE were measured at the end of each 3-minute bout. Anaerobic threshold was identified by HRDP and LT methods by experienced physiologists. Paired Student's t-test, Bland-Altman analysis, and Pearson correlation were used for data analysis (α = 0.05). As results, there was agreement between HRDP and LT methods for HR, while RPE presented significant higher values for the HRDP method, resulting in an absence of acceptable agreement between methods. In addition, strong relationships (p ≤ 0.001) were verified between methods of AT determination for HR (r = 0.786) and RPE (r = 0.916). Therefore, based on the agreement between HRDP and LT methods, the HR determined by HRDP may be a valid parameter used for the intensity prescription of water-based stationary running exercise in young men during water aerobics programs and may be considered more reliable than RPE.

[Water aerobics training: selection and control of the exercise intensity using the Borg scale]

OBJECTIVE

To evaluate the opportunity of Borg scale using for applying and monitoring the aerobic training intensity in the pool as well as the relationship between the Borg scale and the heart rate (HR) in the aquatic environment.

MATERIAL AND METHODS

The study involved 11 healthy individuals (mean age 46.4±7.5 years). After a cardiopulmonary test on a treadmill and a probation lesson the training was conducted in the pool using a set of basic aerobic exercises lasting 45 minutes. During training the subjects had to maintain a load level corresponding to 12-14 points on the Borg scale. Every 10 minutes of the main training part the heart rate was calculated and the rating of perceived exertion (RPE) was determined according to the Borg scale.

RESULTS

The average heart rate in the main part of the training was 126.8±14.0 beats/min. The intensity of aerobic exercise was 82% of the maximum heart rate determined during the cardiopulmonary test and 68% of the reserve heart rate which corresponded to a high level of intensity. Between the heart rate and the Borg scale a significant correlation was found in the first period of training (r=0.67, p<0.02). At RPE 12-13 in almost ¹/₂ cases the subjects felt a subjectively lower intensity of the load than they actually performed (by heart rate) while at RPE 14 a high percentage of coincidences was observed between different measurement methods (p<0.05).

CONCLUSION

During water aerobics training the use of the Borg scale to prescribe and maintain a level of exercise allows to achieve a sufficient intensity level which is necessary to improve cardiorespiratory fitness and physical performance in order to influence risk factors for cardiovascular disease. The Borg Scale as a stand-alone method of controlling intensity when using water-based aerobic training, especially with high-intensity training should be used with caution. Further investigation is needed to determine the relation between subjective measures of exercise intensity and HR and validity of their use during water aerobics training.

Relationship between Oxygen Uptake, Heart Rate, and Perceived Effort in an Aquatic Incremental Test in Older Women

Different parameters can be used to control the intensity of aerobic exercises, a choice that should consider the population and exercise environment targeted. Therefore, our study aimed to verify the relationship between oxygen uptake (VO₂), heart rate (HR), rating of perceived exertion (RPE), and cadence during an aquatic incremental test in older women. Nine older women (64.3 ± 4.4 years) engaged in a water-based aerobic training performed an aquatic incremental test using the stationary running exercise (cadence increases of 15 b·min⁻¹ every 2 min) until participants’ volitional exhaustion. VO₂, HR, and RPE data were measured, and the percentage of peak VO₂ (%VO_2peak) and percentage of maximal HR (%HR_max) were calculated. Linear and polynomial regression analyses were performed (α = 0.05). Polynomial regressions revealed the best adjustments for all analyses. Data showed a significant relationship (p < 0.001) between %VO_2peak and %HR_max (r = 0.921), %VO_2peak and RPE (r = 0.870), and %HR_max and RPE (r = 0.878). Likewise, significant relationships between cadence (p < 0.001) and %VO_2peak (r = 0.873), %HR_max (r = 0.874), and RPE (r = 0.910) were also observed. In summary, the physiological, subjective, and mechanical variables investigated were highly associated during an aquatic incremental test to exhaustion in older women. Therefore, these different parameters can be employed to adequately prescribe water-based programs according to preference and availability.

Water-based continuous and interval training in older women: Cardiorespiratory and neuromuscular outcomes (WATER study)

The purpose of this study was to investigate the effects of two water-based aerobic programs on cardiorespiratory and neuromuscular outcomes in older women. Forty-one women (60 to 75 years old) volunteered to participate in the study. Participants were randomized into a water-based continuous (CTG; n = 21; 63.9 ± 2.5 years) or an interval (ITG; n = 20; 64.8 ± 3.6 years) aerobic training group. Both training programs were performed for 12 weeks (45-min sessions twice a week), with exercise intensity based on rating of perceived exertion (Borg's RPE 6-20 Scale). Pre and post training assessments of cardiorespiratory and neuromuscular outcomes were performed. Data analyses were conducted using Generalized Estimating Equations and Bonferroni post-hoc test (α = 0.05). After the intervention, the CTG and the ITG displayed similar improvements in time to exhaustion (8% vs. 11%), peak oxygen uptake (9% vs. 7%), maximal dynamic knee extension strength (5% vs. 6%), dynamic muscular endurance of knee extensors (10% vs. 11%), maximal vastus lateralis electromyographic signal amplitude (13% vs. 35%), as well as an increase in muscle thickness (5% vs. 6%) and decrease in muscle echo intensity (-2% vs. -3%) of the quadriceps femoris. In conclusion, older women benefited from water-based exercise training prescribed based on participants' RPE, with both the interval and the continuous training programs resulting in similar increases in the cardiorespiratory and neuromuscular parameters.

Energy expenditure and EPOC between water-based high-intensity interval training and moderate-intensity continuous training sessions in healthy women

The present study compared the energy expenditure (EE) during and after two water aerobics protocols, high-intensity interval training (HIIT) and moderate continuous training (CONT). A crossover randomized design was employed comprising 11 healthy young women. HIIT consisted of eight 20s bouts at 130% of the cadence associated with the maximal oxygen consumption (measured in the aquatic environment) with 10s passive rest. CONT corresponded to 30 min at a heart rate equivalent to 90-95% of the second ventilatory threshold. EE was measured during and 30 min before and after the protocols and excess post-exercise oxygen consumption (EPOC) was calculated. Total EE during session was higher in CONT (227.62 ± 31.69 kcal) compared to HIIT (39.91 ± 4.24 kcal), while EE per minute was greater in HIIT (9.98 ± 1.06 kcal) than in CONT (7.58 ± 1.07 kcal). Post-exercise EE (64.48 ± 3.50 vs. 63.65 ± 10.39 kcal) and EPOC (22.53 ± 4.98 vs.22.10 ± 8.00 kcal) were not different between HIIT and CONT, respectively. Additionally, oxygen uptake had already returned to baseline fifteen minutes post-exercise. These suggest that a water aerobics CONT session results in post-exercise EE and EPOC comparable to HIIT despite the latter supramaximal nature. Still, CONT results in higher total EE.