ABSTRACT

Context: The use of essential oils through aromatherapy to enhance physical, mental, spiritual and emotional balance has increased in recent years. The exact benefits of using aromatherapy with exercise have yet to be established.
Objective: The effect of aromatherapy on a 15 minute exercise bout was examined in this double - blind laboratory experiment.
Design: Eight apparently healthy sedentary college age students [four male and four female] volunteered to participate in this investigation. All subjects were screened for olfactory sensation followed by three separate trials walking on a motorized treadmill at a speed of 93.8 meters/minute for 15 minutes.
Measures: Prior to each trial, one of three aromas [lavender, peppermint or placebo] were administered to the subject while walking. During this time, physiological responses (oxygen consumption [VO2], respiratory exchange ratio [RER] and minute ventilation [VE]) were assessed every three minutes using open circuit spirometry and heart rate using telemetry. A subjective measure of the subjects perceived exertion [RPE] was also obtained at each interval.
Results: There were no significant differences [P = 0.5] found in resting or exercise heart rate, oxygen consumption, minute ventilation or perceived exertion among the three trials. The only exception was a trend for resting heart rate to increase with the lavender treatment.
Conclusions: The results from these data suggest that peppermint and lavender do not significantly impact physiological variables during a 15 minute exercise bout, suggesting that potential benefits from these aromas during exercise may require longer exercise duration.

INTRODUCTION

The success of athletic and physical performance can be attributed to a number of variables including training and genetics. In order to enhance performance, athletes are known to try a variety of aids to enhance performance and boost their chances of winning. The term "ergogenic aids" identifies those agents or procedures which if followed before a competition will potentially enhance the athlete's performance [Wilmore and Costill, 1998]. Common examples include carbohydrate supplementation, caffeine ingestion and blood doping for increases in endurance performance. Sodium bicarbonate loading is recognized for its potential ergogenic effect on sprinting events. Creatine supplementation and anabolic steroids have been reported in the lay and scientific press as a means of increasing strength and endurance [Wilmore and Costill, 1998]. Carbohydrate supplementation is allowed before and during competition. Caffeine is also allowed, however a urinary concentration cutoff of 12 mcg/mL [Untied States Olympic Committee] and 15 mcg/mL [National Collegiate Athletic Association] prohibits massive dosages of it before a competition [Allen and Hanbury, 1992] Blood doping, [a process of reinfusion of blood after extraction followed by 3 weeks of training to increase ones hematocrit and hemoglobin levels] and anabolic steroids [simulation of testosterone to increase skeletal muscle] are banned due to medical and ethical reasons [Wilmore and Costill, 1998]. Creatine supplementation is allowed with no established guidelines due to the lack of literature addressing its effects both on the short and long term.

Aromatherapy, another possible ergogenic aid, has been growing in recent years and has received much attention by both traditional and alternative medicine practitioners. However, there is very little evidence which supports or refutes the claims made by merchants, practitioners, and manufacturers [Vickers, 1997]. Since smell is the least understood of all our senses [Guyton, 1991] it is logical to understand why the number of discrepancies exist within the lay and scientific literature regarding the validity of aromatherapy. Buckle argues that aromatherapy is becoming more and more valuable in holistic nursing practice and should be a part of nursing protocols [Buckle, 1998]. Martin [1996] suggests that drawing conclusions regarding aromatherapy is premature since much of the data is qualitative as much of it is based on pure historical content and anecdotal reports from individuals [Guyton, 1991]. Dodd and Sinner [1992] have argued against aromatherapy secondary to the poor follow-up of clients after sessions. Additionally many reports are purely subjective in nature and cannot be considered truly scientific [Lis-Valchin, 1997].

Inhaling peppermint is reported to be a stimulant for increased energy which would certainly benefit any athletic or non-athletic individual during an exercise bout [Burton-Goldburg, 1993]. By definition, peppermint could be considered an ergogenic aid. Lavender is marketed as an aroma which promotes relaxation and a calming effect [Buckle, 1998]. Although lavender would not qualify as an ergogenic aid, it would certainly be beneficial to an individual before and after competition to promote relaxation, improve concentration prepare for competition and speed recovery from competition. As with any ergogenic aid, multiple questions arise regarding legal and ethical issues. Also important is the additive being used a substance the athlete would normal consume or use in everyday life [Wilmore-Costill, 1998].

The purpose of this pilot investigation was to examine the potential benefits that two common aromas might have on basic physiological measures before and during a 15-minute exercise bout. There is little evidence in the literature addressing the actual physiological responses after the introduction of an aroma during exercise. It was hypothesized that heart rate [HR], oxygen consumption [VO2] and ventilation [VE] would increase and respiratory exchange ratio [RER] and rating of perceived exertion [RPE] would decrease with peppermint. HR, VO2 and VE would decrease and RER and RPE would increase with lavender.

METHODS

Subjects
Four male and four female apparently healthy college students volunteered to participate in this investigation. Mean ages were 22.5 ± 0.8 for males and 21.75 ± 0.9 for females. These students considered themselves sedentary. In this investigation, an individual was considered sedentary if they did not regularly participate in physical activity more than two days per week at equal to or greater than 60 % of their maximal heart rate. All subjects were familiar with exercise protocols and walking on a motorized treadmill. Following an explanation of the risks and benefits of participation subjects signed a written consent statement. This study was approved by the departmental review board for institutional research of the College of St. Scholastica.
Instrumentation
Oxygen consumption [VO2], minute ventilation [VE ] and respiratory exchange ratio [RER] were obtained via open circuit spirometry using a MedGraphics Cardio 2 metabolic analyzer [Model 790602, St. Paul, MN]. HR was recorded using a Polar Heart Rate Monitor [Model 1901201, Port Washington, NY]. A motorized treadmill [Trackmaster 5000, JAS Manufacturing, Carrollton, TX] was used for the exercise mode. RPE was obtained using the modified Borg scale [ACSM, 1995]
Procedures
Prior to participating in this investigation, subjects agreed to the three half-hour trials over a period of three weeks. During each trial, subjects completed the same protocol, however the aroma was administered in a double blind cross over design.

Prior to data collection, subjects were familiarized with the laboratory setting and the mouthpiece that was used to collect expired gases during each trial. In order to assess each subjectÕs olfactory sensation, they were asked to identify three recognizable aromas: coffee, pine and a placebo [water with food coloring made to resemble other aroma mixtures]. As subjects confirmed their olfactory sensation by recognizing each aroma, their suitability for participation was confirmed.

After acclimation to the laboratory, subjects returned once per week for three weeks. Each week a different aroma was administered in a double blind fashion. The administration of the essential oil was delivered through a sealed plastic container with the oil concentrated on a sterile cotton pad. Subjects inhaled the aroma with only nose breathing. Prior to each trial, a technician established a random order regarding the administration of each aroma and labeled the three containers. These were left for the investigators to use for each trial. The technician was not present for the trials.

Each subject inhaled the aroma for one minute and began walking on the treadmill at a speed of 93.8 meters/minute for 15 minutes. At every three-minute interval, the subject's HR, VO2, VE and RPE were obtained and recorded. Also at each interval the designated aroma was again administered using the sealed container for a period of 60 seconds. After the 15-minute period was completed, subjects walked for five minutes at a speed of 53.6 meters/minute. Recovery heart rates were obtained until it was confirmed that subjects had returned to within 20 beats of their pre-exercise heart rate.

RESULTS

Each subject completed three separate exercise bouts of treadmill walking lasting 15 minutes. During each bout subjects inhaled one of three samples in a double blind fashion. Table 1 contains the data obtained from analysis of expired gases Oxygen consumption [VO2] minute ventilation [VE] and Respiratory Exchange Ratio [RER] remained the same among all three trials.

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VO2 =total body O2 consumption
VE = VT [Tidal Volume] * Breaths per minute
RER = VCO2 / VO2

TABLE 1. Physiological Variables Variable Placebo Peppermint Lavender P VO2 [ml/kg/min] 12.74 ± 1.4 12.92 ± 1.9 12.85 ± 1.4 NS RER 0.95 ± 0.07 0.92 ± 0.08 0.92 ± 0.06 NS VE [L/min] 25.65 ± 3.7 25.16 ± 4.2 25.18 ± 4.8 NS

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Heat rate response can be found in Table 2. During exercise, heart rates increased approximately 30 beats per minute above pre-exercise rates for all three trials. Based on the rate of exercise intensity which subjects performed, this response was considered normal. The exception to this increase was with the lavender trial which only elicited a 23 beat increase secondary to the higher pre-exercise heart rate of 77 BPM as compared to 71 BPM for the peppermint and placebo trial.

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* beats per minute

TABLE 2. Heart Rate And Rating of Perceived Exertion [RPE] Response Variable Placebo Peppermint Lavender P Pre-Exercise HR * 71.25 ± 10.1 71.75 ± 8.0 77.13 ± 8.5 NS Exercise HR * 99.13 ± 11.3 100.13 ± 9.9 100.9 ± 9.9 NS RPE 2.1± 0.9 2.3 ± 0.9 2.4 ± 0.8 NS

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Subjective measures of the modified Borg Scale or Rating of Perceived Exertion [RPE] were obtained and these results demonstrated a slight but non Š significant increase for the peppermint and lavender [2.3 and 2.4] respectively compared to a 2.1 for the placebo trial. These data may be found in Table 2. An RPE of 2 equates to a perception of light work. Table 3 is a composite of the RPE scale {Powers and Howley, 1998].

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* beats per minute

TABLE 3. Rating of Perceived Exertion Revised Scale Rating Perception 0 Nothing at all 0.5 Very, very light [just noticeable] 1 Very light 3 Light 4 Somewhat hard 5 Heavy 6 - 7 Very heavy 8 - 9 - 10 Very, very heavy [almost max] - Maximal

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DISCUSSION

The use of aromatherapy is rapidly growing within western society. It is obvious from the literature that there are vast differences in opinion regarding the efficacy, validity and the overall claims towards the role of aromatherapy in all aspects of medicine, particularly preventative and rehabilitative medicine. Exercise does fall into both categories, preventive and rehabilitative, therefore the use of aromatherapy in concert with exercise is quite popular. Although it is claimed that peppermint may accentuate energy by stimulating the adrenal cortex [Burton-Goldburg, 1993] it is not known what dosage and how this increased energy may affect exercise performance. In the present investigation, peppermint had no effect on resting or exercise heart rate during 15 minutes of moderate treadmill walking.

Lavender is claimed as having a calming effect on the body, which will facilitate relaxation [Martin, 1996]. Buckle [1998] has reported that lavender when inhaled has a role in relaxation and improved comfort and coping of patients in critical care. However in the present investigation, inhalation of lavender increased resting heart rate and would be counterproductive if introduced to a critical care patient in need of relaxation.

There are a number of factors in this pilot study which may have affected the results. The research hypothesis stated the peppermint treatment should have elicited a higher heart rate and higher oxygen consumption and a lower perceived exertion while the lavender treatment would have the opposite effect. All trials elicited no changes in measured values as would be the expected effect from the placebo treatment [water and food coloring].

The length of the exercise bout may have affected the results. A 15-minute walk on a treadmill at 93.8 meters/ minute translates to a short but brisk walk for the average individual [3.5 miles/hour]. For example, a 70-kg individual would expend approximately 60 kcals of energy during a 15-minute walk at this speed. This short time period coupled with a low caloric output may not have been an adequate metabolic stimulus for peppermint to exert its effects on heart rate response and the measured physiological values. Further, it is not known what mechanisms play a role with aromatherapy and metabolism. At 15 minutes of exercise the average individual is just beginning to achieve a true point when oxygen demands equal oxygen availability or more commonly referred to as steady state of oxygen consumption [Powers and Howley, 1998]. Additionally, fat metabolism has not begun to significantly contribute as an energy source as noted by the RER. A RER at 0.90 indicates 33 % fat is being consumed for energy whereas at 0.95 only 17 % fat are being consumed [Powers and Howley, 1998]. It is possible that aroma may have more beneficial effect when fat is the major fuel source as opposed to carbohydrate. However, Lis-Balchin [1997] has reported that peppermint has a sedative effect on smooth muscle in vitro. It is unknown in what other condition peppermint might exert sedative effects, such as the primary fuel, either carbohydrate of fat during exercise.

Rating of perceived exertion [RPE] is considered a good indicator of an individual's subjective effort and provides a quantitative assessment of an individual's progress during exercise testing or an exercise bout [ACSM, 1995]. However, RPE has its critics particularly when related to exercise testing which often precedes the basis of exercise training. Whaley has reported that using RPE during exercise training may need to establish a perceptual-physiological relationship prior to exercise [Whaley, et al, 1997]. In the present investigation, it may have assisted the subject's understanding of RPE if the time allowed in practice before the aromas were introduced.

The inability of lavender to decrease the measures may have been partly explained by the method used to introduce aroma to each subject. We used a sealed container that the subject inhaled for approximately 60 seconds. This particular method is not recommended as an introductory method. Buckle [1998] suggests that during direct inhalation, the individual inhale for 5 to 10 minutes. The reason for the difference was the logistics of inhaling while walking on the treadmill. It is recommended that in future investigations that a mask be used as opposed to a mouthpiece for gas sampling, using caution to only use one mask per aroma. We were unable to use a mask due to the time constraints for data collection. By doing this one could control the amount and frequency of aroma oil and maintain a constant measure of expired gases.

These data are disappointing regarding aromatherapy and exercise performance, however, given the above limitations regarding time and introduction of aroma, these results are understandable. Welker and co-workers [1998] also found no effect on physiological values using similar conditions and exercise time. Given a longer exercise bout and perhaps different exercise intensities, the effects of aroma may be more evident. Further research should explore the relationship of aroma with exercise bouts up to 120 minutes and intensities varying as low as 40% of VO2MAX, which would equate walking, and up to 70 % VO2MAX, which would equate moderate running, speeds. These varying conditions will appropriately reflect the habits of more individuals with different degrees of exercising intensities.

Finally, an issue which once the benefits of aroma on exercise performance is established, the questions regarding their ethical use must be addressed. Most recently, creatine supplementation has fallen into close scrutiny. Although there seems to be no serious side effects with its use during athletic events, is it really fair to allow its use in competition as it may enhance an participant's performance, giving them an advantage over one who may not choose to use the supplement or may not have access to it. The same could eventually emerge with aromatherapy. Not every participant may have the opportunity have access to it, therefore, those that do have access will have an unfair advantage during athletic contests.

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