Mauricio Garzon

Effects of Sauna Alone and Postexercise Sauna Baths on Blood Pressure and Hemodynamic Variables in Patients With Untreated Hypertension

J Clin Hypertens (Greenwich). 2012;00:00–00 ©2012 Wiley Periodicals, Inc.

Cardiovascular and hemodynamic responses on dryland vs. immersed cycling

OBJECTIVES To investigate the effect of water immersion on oxygen uptake (VO2) and central hemodynamic responses during incremental maximal exercise at the same external power output (P ext) and recovery on an immersible ergocycle vs. a dryland ergocycle. DESIGN Cross-over design study. METHODS Twenty healthy participants (32 ± 7 years; 173 ± 6 cm; 71.7 ± 9.7 kg) performed maximal incremental exercise tests while pedalling either immersed on immersible ergocycle (Hydrorider(®)) or on dryland ergocycle (Ergoline 800 S; Bitz, Germany). Initial P ext of dryland ergocycle protocol was set at 25 W and increased by 25 W every minute until exhaustion. P ext on immersible ergocycle was controlled by pedalling rate (rpm). Initial rpm was set at 40 rpm and was increased by 10 rpm until 70 rpm and thereafter by 5 rpm until exhaustion. Gas exchange and central hemodynamic parameters were measured continuously during exercise and a 5-min recovery period. Reported VO2, stroke volume, cardiac output (Q) and arteriovenous difference (C(a-v)O2) were compared. RESULTS During exercise on immersible ergocycle, VO2 and C(a-v)O2 were lower (P < 0.0001) whereas stroke volume and Q were higher (P < 0.05) relative to a dryland ergocycle exercise of equivalent P ext. CONCLUSIONS During exercise and recovery in immersion, (VO2) and arteriovenous difference were reduced in healthy young participants, while stroke volume and cardiac output were increased for the same P ext. During the recovery, central hemodynamics responses remained higher in immersible ergocycle.

Biomechanical analysis to determine the external power output on an immersible ergocycle.

Abstract The external power output (Pext) is unknown during chest-level immersion exercise on water immersible ergocycles (IE). This knowledge will allow the practitioner to prescribe accurately exercise on an IE to the same workload on dryland ergocycle (DE). To develop a mathematical model to calculate Pext during chest-level immersion exercise on IE at different pedalling rates (rpm) taking into account the water external force exerted on the legs and pedalling mechanism. Thirty healthy participants (age: 33 ± 10 years) performed a maximal incremental exercise test on IE (chest-level immersion) and on a DE. Pedalling rate was increased by 10 rpm every minute beginning at 40 till 120 rpm. Pext was calculated by applying the general fluid equation on all elements exposed to water external force exertions (legs and pedalling system). Regression analysis yielded the following equations to determine (1) IE Pext (W) based on pedalling rate (rpm): Pext (W) = 0.0004 (rpm)2.993 (r2 = 0.99, SEE = 7.6 W, p < 0.0001) and (2) when DE Pext (W) is known, IE pedalling rate (rpm) = 13.91 × DE Pext (W)0.329 (r2 = 0.99, SEE = 1.5 W, p < 0.0001). This study provides a mathematical model based on the general fluid equation to calculate IE Pext during chest-level immersion exercise using pedalling rate (rpm), IE pedalling system physical characteristics and lower limb size. This model can be used to determine Pext for any IE type for exercise training prescription.

Effects of sauna alone versus postexercise sauna baths on short-term heart rate variability in patients with untreated hypertension.

PURPOSE: We measured the effects of sauna bathing alone or a 30-minute exercise session followed by sauna bathing on short-term heart rate variability (HRV) in subjects with untreated hypertension. METHODS: Ten patients with untreated hypertension (age 59 ± 10 years) were randomly assigned to (1) a control resting session, (2) two 8-minute sauna-only sessions (S), or (3) a 30-minute aerobic exercise session at 75% of maximal heart rate followed by a sauna session (ES). Spectral analysis of HRV was measured with a Polar S810 heart rate monitor at baseline, during the sauna session, and 15 and 120 minutes after the sauna session (T15 and T120). A Fast Fourier Transformation was used to quantify the power spectral density of the low-frequency (LF) and high-frequency (HF) bands. RESULTS: For S and ES conditions, LF (NU, normalized unit) and LF/HF were significantly higher (P < .05 and P < .01) in the first and second sauna sessions, and HF (NU) was significantly lower (P < .05, first sauna). At baseline and T15 for S and ES versus control, LF (NU) and LF/HF were significantly higher (P < .05), and HF (NU) was significantly lower (P < .05), without any effect of the 30-minute exercise session. CONCLUSIONS: A single sauna session induced a significant alteration of autonomic cardiovascular control in patients with untreated hypertension, with an increased sympathetic and decreased parasympathetic drive. These alterations were normalized within 15 to 120 minutes after sauna bathing. Additional studies are required to document long-term effects of chronic sauna bathing on autonomic control in patients with hypertension.

Immersible ergocycle prescription as a function of relative exercise intensity

Purpose The purpose of this study was to establish the relationship between various expressions of relative exercise intensity percentage of maximal oxygen uptake (%VO2max), percentage of maximal heart rate (%HRmax), %VO2 reserve (%VO2R), and %HR reserve (%HRR)) in order to obtain the more appropriate method for exercise intensity prescription when using an immersible ergocycle (IE) and to propose a prediction equation to estimate oxygen consumption (VO2) based on IE pedaling rate (rpm) for an individualized exercise training prescription. Methods Thirty-three healthy participants performed incremental exercise tests on IE and dryland ergocycle (DE) at equal external power output (Pext). Exercise on IE began at 40 rpm and was increased by 10 rpm until exhaustion. Exercise on DE began with an initial load of 25 W and increased by 25 W/min until exhaustion. VO2 was measured with a portable gas analyzer (COSMED K4b2) during both incremental tests. On IE and DE, %VO2R, %HRmax, and %HRR at equal Pext did not differ (p > 0.05). Results The %HRR vs. %VO2R regression for both IE and DE did not differ from the identity line %VO2R IE = 0.99 × HRR IE (%) + 0.01 (r2 = 0.91, SEE = 11%); %VO2R DE = 0.94 × HRR DE (%) + 0.01 (r2 = 0.94, SEE = 8%). Similar mean values for %HRmax, %VO2R, and %HRR at equal Pext were observed on IE and DE. Predicted VO2 obtained according to rpm on IE is represented by: VO2 (L/min) = 0.000542 × rpm2 − 0.026 × rpm + 0.739 (r = 0.91, SEE = 0.319 L/min). Conclusion The %HRR–%VO2R relationship appears to be the most accurate for exercise training prescription on IE. This study offers new tools to better prescribe, control, and individualize exercise intensity on IE.

Thermoneutral immersion exercise accelerates heart rate recovery: A potential novel training modality.

Abstract This study compared heart rate recovery (HRR) after incremental maximal exercise performed at the same external power output (Pext) on dry land ergocycle (DE) vs. immersible ergocycle (IE). Fifteen young healthy participants (30 ± 7 years, 13 men and 2 women) performed incremental maximal exercise tests on DE and on IE. The initial Pext on DE was 25 W and was increased by 25 W/min at a pedalling cadence between 60 and 80 rpm, while during IE immersion at chest level in thermoneutral water (30°C), the initial Pext deployment was at a cadence of 40 rpm which was increased by 10 rpm until 70 rpm and thereafter by 5 rpm until exhaustion. Gas exchange and heart rate (HR) were measured continuously during exercise and recovery for 5 min. Maximal HR (DE: 176 ± 15 vs. IE 169 ± 12 bpm) reached by the subjects in the two conditions did not differ (P > .05). Parasympathetic reactivation parameters (ΔHR from 10 to 300 s) were compared during the DE and IE HR recovery recordings. During the IE recovery, parasympathetic reactivation in the early phase was more predominant (HRR at Δ10–Δ60 s, P < .05), but similar in the late phase (HRR at Δ120–Δ300 s, P > .05) when compared to the DE condition. In conclusion, incremental maximal IE exercise at chest level immersion in thermoneutral water accelerates the early phase parasympathetic reactivation compared to DE in healthy young participants.

Discussion of "Cardiorespiratory alterations induced by low-intensity exercise performed in water or on land"

We have read with great interest the article by Ayme et al. (2015), recently published in Applied Physiology, Nutrition, andMetabolism, that was on cardiorespiratory alterations induced by low-intensity exercise performed inwater or in land. The authors found no differences in echocardiographic parameters during exercise (at approximately 37% of dry-land peak oxygen uptake (VO2peak) and higher respiratory rate and ventilation in immersed versus dry-land ergocycle. We would like to make several comments regarding this publication, particularly for the Methods section. The authors stated that “previous studies failed to demonstrate cardiorespiratory differences between the 2 conditions under the threshold of 40%–60% VO2peak”. Our research group has demonstrated that oxygen uptake (VO2) is reduced during immersed ergocycling, even at very low exercise intensities (Garzon et al. 2015), owing principally to a reduced arteriovenous difference. As a consequence, VO2peak measured during dryland ergocycling is not similar to the one measured during immersed ergocycling and can be reduced by 27% in immersion (Garzon et al. 2015). Therefore, matching exercise intensity with a percentage of dry-land VO2peak value (37% in this study) (Ayme et al. 2015) may represent a potential bias and would lead to a higher relative percentage of exercise intensity in the water condition. As an example, 38% of VO2peak for dry-land conditions (75 W or 60 revolutions per minute (rpm), Table 1 (Garzon et al. 2015)) correspond to 46% of VO2peak measured on immersed ergocycling. Therefore, this could explain why respiratory rate and ventilation were found higher during exercise in water condition (Table 3) (Ayme et al. 2015). However, this result is in contradiction with a previous study demonstrating similar respiratory rate and ventilation at 60% of VO2peak (dry-land condition) (Brechat et al. 1999). We also demonstrated no differences in respiratory rate and ventilation at submaximal and maximal intensities matched with similar external power output (Garzon et al. 2012). To avoid this problem, we developed a biomechanical method to match the exercise intensity according to a similar external power output for immersed and dry-land ergocycles (Garzon et al. 2014, 2015). As well, in the Methods section, the model of the aquabike and the corresponding rpm used in the study is not indicated (Ayme et al. 2015). This can havemajor impact on the VO2/rpmrelationship, dependingon theaquabikemodelused (Giacomini et al. 2009) and also on the reproducibility of the study results by others research groups. Additionally, the authors stated that