Similar results for face mask versus mouthpiece

Journal of Sports Sciences

ISSN: 0264-0414 (Print) 1466-447X (Online) Journal homepage: http://www.tandfonline.com/loi/rjsp20

Similar results for face mask versus mouthpiece during incremental exercise to exhaustion Dale R. Wagner & Nicolas W. Clark To cite this article: Dale R. Wagner & Nicolas W. Clark (2016) Similar results for face mask versus mouthpiece during incremental exercise to exhaustion, Journal of Sports Sciences, 34:9, 852-855, DOI: 10.1080/02640414.2015.1075058 To link to this article: http://dx.doi.org/10.1080/02640414.2015.1075058

Published online: 04 Aug 2015.

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Date: 23 April 2016, At: 13:04

JOURNAL OF SPORTS SCIENCES, 2016 VOL. 34, NO. 9, 852–855 http://dx.doi.org/10.1080/02640414.2015.1075058

Similar results for face mask versus mouthpiece during incremental exercise to exhaustion Dale R. Wagner and Nicolas W. Clark

Downloaded by [Utah State University Libraries] at 13:04 23 April 2016

Human Movement Science Program, Utah State University, Logan, UT, USA ABSTRACT

ARTICLE HISTORY

Investigations in the 1990s evaluated the influence of breathing assemblies on respiratory variables at rest and during exercise; however, research on new models of breathing assemblies is lacking. This study compared metabolic gas analysis data from a mouthpiece with a noseclip (MOUTH) and a face mask (MASK). Volunteers (7 males, 7 females; 25.1 ± 2.7 years) completed two maximal treadmill tests within 1 week, one MOUTH and one MASK, in random order. The difference in maximal oxygen consumption (VO2max) between MOUTH (52.7 ± 11.3 ml · kg−1 · min−1) and MASK (52.2 ± 11.7 ml · kg−1 · min−1) was not significant (P = 0.53). Likewise, the mean MOUTH–MASK differences in minute ventilation (VE), fraction of expired oxygen (FEO2) and carbon dioxide (FECO2), respiration rate (RR), tidal volume (Vt), heart rate (HR), and rating of perceived exertion (RPE) at maximal and submaximal intensities were not significant (P > 0.05). Furthermore, there was no systematic bias in the error scores (r = −0.13, P = 0.66), and 12 of the 14 participants had a VO2max difference of ≤3 ml · kg−1 · min−1 between conditions. Finally, there was no clear participant preference for using the MOUTH or MASK. Selection of MOUTH or MASK will not affect the participant’s gas exchange or breathing patterns.

Accepted 16 July 2015

Introduction Maximal oxygen consumption (VO2max) is the criterion or gold standard measurement of aerobic fitness, and it is a commonly used assessment in healthcare settings as well as for athletic performance evaluation. Modern VO2max assessment is done during an exercise test with the use of an automated system that analyses expired oxygen and carbon dioxide. The participant is tethered to the automated system via plastic tubing and a mouthpiece/noseclip combination (MOUTH). A biteblock, similar to a snorkel, is used to keep the mouthpiece firmly in the mouth, and the noseclip prevents air from escaping through the nostrils. This system can be uncomfortable for participants, particularly during vigorous exercise, as it impairs verbal communication, makes swallowing difficult, and promotes dry mouth. An alternative to the MOUTH is a face mask (MASK) made of pliable rubber that fits over both the nose and mouth. The MASK eliminates or reduces many of the discomforts associated with the MOUTH, allowing for both oral and nasal breathing, swallowing, and verbal communication. A concern is that it might not be possible to get a tight enough seal between the face and the MASK to prevent leakage of expired air, particularly at high ventilation rates of vigorous exercise. Nevertheless, MASKS have performed as well as MOUTH during maximal exercise in children (Mahon, Stolen, & Gay, 1998), congestive heart failure patients (Baran et al., 2001), and aerobically fit adults (Evans & Potteiger, 1995). However, close inspection of the data by Evans and Potteiger (1995), who tested NCAA Division I runners showed a drop in VO2max

CONTACT: Dale R. Wagner © 2015 Taylor & Francis

[email protected]

KEYWORDS

Aerobic capacity; VO2max; oxygen consumption; breathing apparatus; ventilation

from 63.5 ± 8.1 ml · kg−1 · min−1 with the MOUTH to 57.7 ± 8.2 ml · kg−1 · min−1 with the MASK. Although not statistically significant in this study, there is a 9.1% reduction which is physiologically meaningful in an athletic population. Similarly, Brooks and Dawes (2013) concluded that the MASK produced values equal to those of the MOUTH at submaximal intensities, yet the difference in VO2max was significantly (P < 0.05) greater for the MOUTH (59.7 ± 8.7 ml · kg−1 · min−1) compared to the MASK (53.2 ± 3.6 ml · kg−1 · min−1). In contrast, Farley, Ray, and Moynihan (1998) reported a statistically significant increase in VO2max for trained runners when using MASK (56.8 ± 11.2 ml · kg−1 · min−1) compared to MOUTH (53.7 ± 12.0 ml · kg−1 · min−1). Most of the previously cited research was done in the mid1990s. Despite changes in mask geometry and headgear design, PubMed and Scopus searches revealed only two updates on this topic in the past 8 years: a letter to the editor by Bell, Bedbrook, Nguyen, and Mourtzakis, in 2012, and research of a vacuumed mask rather than the more commonly used Hans Rudolph mask by Brooks and Dawes in 2013. The MASK models tested in the pre-twenty-first century studies are now out of date. According to the manufacturer, the current MASK is lighter in weight and differs in wall thickness, geometry, and contact surface area to create a more comfortable fit and superior seal to previous models (K. Rudolph, personal communication, 2015). Furthermore, advances in the processing of expired gas analysis data have improved the precision of VO2max testing (Robergs, Dwyer, & Astorino, 2010). Thus, the purpose of this study was to compare modern MASK and MOUTH systems used for the collection and analysis of metabolic gas exchange.

Utah State University, 7000 Old Main Hill, Logan, UT 84322-7000, USA.

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Methods Experimental approach to the problem A crossover design with the trial order randomised by coin toss was used. Trials were separated by at least 48 h but not more than 1 week.

Participants


Fourteen recreationally active graduate students (7 males, 7 females; 25.1 ± 2.7 years) enrolled in a bioenergetics course volunteered for the study. Prior to participation, participants completed the Physical Activity Readiness Questionnaire (PAR-Q) and signed a written informed consent. The study was approved by the University’s Institutional Review Board (protocol #6017).

Procedures Both MOUTH and MASK trials were conducted at the same time of day, and study participants were instructed to maintain the same diet and activity level during the day leading up to each trial. Prior to the VO2max test, participants’ heights were measured to the nearest 0.1 cm using a wall-mounted stadiometer (Seca 216, Seca Corp., Ontario, CA), and weights were measured to the nearest 0.1 kg with a digital scale (Seca 869, Seca Corp., Ontario, CA). These measurements were taken with the participants wearing only shorts and a t-shirt and without their shoes. Participants were fitted with a Polar T31 heart rate monitor (Polar Electro, Lake Success, NY). The breathing apparatus for the MOUTH trial consisted of the series 2700 model two-way non-rebreathing valve (Hans Rudolph, Inc., Shawnee, KS) fitted with a large rubber snorkelstyle mouthpiece, and a noseclip prevented nasal breathing. The combined dead space of the silicone rubber mouthpiece and two-way valve was 102.9 ml. The same two-way nonrebreathing valve was fitted to a 7450 V2 series face mask (Hans Rudolph, Inc., Shawnee, KS) instead of the mouthpiece for the MASK trial. The dead space of the face mask was 99 ml, and combined with the two-way valve the total dead space was 176.3 ml; however, face geometry also affects the dead space. The mask size (small or medium) was determined by visual inspection. The mask was secured tightly with the manufacturer-provided Velcro headgear and checked for leakage by feeling for air around the mask. Both breathing systems are depicted in Figure 1. Metabolic gas exchange was measured

Figure 1. The breathing assemblies tested: (A) the mouthpiece with noseclip (MOUTH), (B) the face mask (MASK).

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by a ParvoMedics TrueMax 2400 Metabolic Measurement System (ParvoMedics, Sandy, UT). This system was calibrated prior to each testing session according to the manufacturer’s recommendations. Participants ran on a NordicTrack 9600 treadmill (ICON Health & Fitness, Logan, UT). The VO2max protocol was a modification of George’s (1996) protocol that was specifically designed for college students. Following 2 min of standing resting data, the participant jogged at a constant self-selected pace between 4.0 and 7.0 miles · h−1 (6.45–11.29 km · h−1) at 0% grade for 3 min; the same pace was used for both trials. Subsequently, the grade was increased by 1.5% at the beginning of each minute until volitional exhaustion. This individualised protocol resulted in exercise duration of 8–10 min for the majority of participants, which is thought to be the optimal duration for VO2max testing (Astorino et al., 2004; Yoon, Kravitz, & Robergs, 2007). Respiratory variables were averaged every 15 breaths, and the highest 15-breath average was considered the VO2max (Robergs et al., 2010). Heart rate and ratings of perceived exertion (RPEs) were recorded each minute. After both trials were completed, participants were asked which apparatus was more desirable.

Statistical analyses Mean differences in the measured physiological variables between the MOUTH and MASK trials and across exercise intensity levels (rest, end of 3-min submaximal jogging stage, and maximal exertion) were assessed with a two-way (method–intensity) repeated measures analysis of variance. A Bland and Altman (1986) analysis was done to evaluate individual variability and systematic bias. Statistical significance was accepted as P < 0.05. All analyses were conducted with the Statistical Package for Social Sciences (SPSS version 22, IBM, Armonk, NY).

Results Data for the sample are presented in Table I. The order of testing did not influence VO2max (P = 0.54). The difference in VO2max between MOUTH (52.7 ± 11.3 ml · kg−1 · min−1) and MASK (52.2 ± 11.7 ml · kg−1 · min−1) was not significant (P = 0.53), and the two systems were highly correlated (r = 0.97, P < 0.001). Likewise, the mean differences in the fractions of expired oxygen (FEO2) and carbon dioxide (FECO2), peak minute ventilation (VE), respiration rate (RR), tidal volume (Vt), heart rate (HR), RPE, and time to peak effort were not significant (see Table I for P-values and 95% confidence intervals). Similarly, at rest and submaximal intensity there were no significant differences in VO2, FEO2, FECO2, VE, RR, Vt, HR, or RPE (Table I). Additionally, the method– intensity interaction was not significant (P > 0.05) for all variables of interest. Furthermore, there was no systematic bias in the error scores (r = −0.13, P = 0.66; Figure 2), and 12 of the 14 participants had a VO2max difference of ≤3 ml · kg−1 · min−1 between conditions. However, there was a slight positive relation between the absolute differences and the mean (r = 0.21), indicating heteroscedasticity (Nevill & Atkinson, 1997); thus, the coefficient of variation was calculated (CV = 3.7%). Finally, there was no clear participant preference for using the MOUTH or MASK as 6 participants preferred the MOUTH and 8 the MASK.

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D. R. WAGNER AND N. W. CLARK

Table I. Experimental data (mean ± SD; N = 14).


Variable Resting data VO2 (ml · kg−1 · min−1) VO2 (L · min−1) FEO2 FECO2 VE (L · min−1) RR (breaths · min−1) Vt (L) HR (beats · min−1)

MOUTH

MASK

P-value

95% CI

1.5 0.16 0.6 0.4 3.5 5.3 0.26 13

4.8 0.35 17.1 3.4 8.8 17.5 0.75 85

± ± ± ± ± ± ± ±

0.8 0.13 0.5 0.3 2.8 3.8 0.19 16

0.09 0.12 0.49 0.06 0.19 0.49 0.42 0.62

−0.1 −0.01 −0.4 −0.0 −0.6 −1.9 −0.10 −9

to to to to to to to to

1.6 0.12 0.2 0.3 2.9 3.8 0.23 6

Submaximal data (after 3 min jogging at VO2 (ml · kg−1 · min−1) 33.3 2.41 VO2 (L · min−1) 15.5 FEO2 4.7 FECO2 43.6 VE (L · min−1) 33.0 RR (breaths · min−1) 1.94 Vt (L) −1 151 HR (beats · min ) RPE 9.5

0% grade) ± 5.6 ± 0.73 ± 0.6 ± 0.5 ± 14.1 ± 7.5 ± 0.54 ± 20 ± 1.7

33.9 2.45 15.7 4.6 46.1 34.0 2.01 151 9.9

± ± ± ± ± ± ± ± ±

5.7 0.73 0.5 0.4 15.8 8.6 0.58 23 1.9

0.52 0.52 0.13 0.16 0.12 0.52 0.23 0.90 0.42

−2.3 −0.17 −0.4 −0.1 −5.7 −4.2 −0.18 −6 −1.3

to to to to to to to to to

1.2 0.09 0.1 0.3 0.7 2.2 0.05 7 0.6

Maximal data VO2 (ml · kg−1 · min−1) VO2 (L · min−1) FEO2 FECO2 VE (L · min−1) RR (breaths · min−1) Vt (L) HR (beats · min−1) RPE Exercise time (s)

± ± ± ± ± ± ± ± ± ±

52.2 3.70 16.8 4.3 93.9 54.8 2.44 186 19.1 562.3

± ± ± ± ± ± ± ± ± ±

11.7 0.96 0.5 0.5 22.1 10.3 0.49 10 1.1 106.2

0.53 0.30 0.07 0.06 0.67 0.18 0.20 0.39 0.11 0.16

−1.1 −0.05 −0.3 −0.0 −5.0 −5.8 −0.04 −2 −0.1 −5.2

to to to to to to to to to to

2.1 0.16 0.0 0.3 3.3 1.2 0.18 5 0.6 28.7

5.5 0.40 17.0 3.5 9.9 18.4 0.82 83

52.7 3.76 16.7 4.4 93.0 52.5 2.51 188 19.4 574.1

± ± ± ± ± ± ± ±

11.3 1.00 0.5 0.5 21.8 8.2 0.46 13 1.0 116.5

Note: VO2 = oxygen consumption; FEO2 = fraction of expired oxygen; FECO2 = fraction of expired carbon dioxide; VE = minute ventilation; RR = respiration rate; Vt = tidal volume; HR = heart rate; RPE = rating of perceived exertion

Figure 2. Bland–Altman plot of VO2max (ml · kg−1 · min−1); solid line = bias, dashed lines = ±2 SD.

Discussion The main finding from this study was that there was no difference in metabolic gas exchange (VO2, FEO2, FECO2), respiratory parameters (VE, RR, Vt), performance, or perceived effort between MOUTH and MASK at rest, submaximal, or maximal exercise in a group of recreationally fit graduate students. Research comparing breathing assemblies for exercise tests from the past 10 to 20 years had equivocal results. Farley et al. (1998) reported that MASK produced higher VO2 and VE at both submaximal and

maximal intensities for runners, but Evans and Potteiger (1995) found no statistically significant difference in VO2max between breathing assemblies despite a mean increase of 5.8 ml · kg−1 · min−1 for MOUTH. Saey et al. (2006) reported no difference in VO2, VE, or endurance time between breathing interfaces for COPD patients who cycled at a constant work rate of 80% VO2 peak. However, they noted lower end exercise values during MASK suggestive of air leakage. More recently, Bell et al. (2012) reported no differences in peak VO2, power, exercise time, Vt, or HR between MOUTH and MASK during incremental cycle ergometer tests; however, peak VE was 10% higher for MASK. They theorised that not being able to breathe through the nose or use pursed-lips breathing during the MOUTH trial might have contributed to the reduction in VE. It should be noted that all of these previous studies used older MASK models. Even the relatively recent Bell et al. (2012) study used a series 7400 MASK, whereas we used the newer 7450 series. According to the manufacturer, the goal of each new MASK series is to create a superior fit and seal to minimise leakage, and this is accomplished through changes in face mask geometry, silicone wall thickness, and headgear design and attachment (K. Rudolph, personal communication, 2015). Finally, there was no clear preference for one breathing assembly over the other. Those who preferred the MASK cited improved comfort, less dry mouth, and being able to breathe through the nose as advantages. MOUTH advocates claimed it was easier to breathe and did not restrict vision as much as the MASK.

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In conclusion, there were no significant differences in gas exchange or breathing patterns between MOUTH and MASK. When fitted properly, either breathing apparatus should produce valid results at both submaximal and maximal exercise intensities. Previously published research on this topic included older face mask models. According to the manufacturer, the newer MASK models offer improved comfort and fit, which should minimise previous concerns of leakage, particularly at high exercise intensities.

Disclosure statement No potential conflict of interest was reported by the authors.


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