Ammonia Inhalation Does Not Increase Deadlift 1-Repetition Maximum in College-Aged Male and Female Weight Lifters

Abstract

Vigil, JN, Sabatini, PL, Hill, LC, Swain, DP, and Branch, JD. Ammonia inhalation does not increase deadlift 1-repetition maximum in college-aged male and female weight lifters. J Strength Cond Res 32(12): 3392–3397, 2018—Ammonia inhalant use by powerlifters and weight lifters is a prevalent practice with little research support for improved performance. The purpose of this study was to investigate the effects of ammonia as a stimulant on athletic performance during a deadlift 1-repetition maximum (1RM) absolute strength test. Subjects (men: n = 10, mean ± SD age = 21 ± 1 year, mass = 72.5 ± 6.8 kg; and women: n = 10, age = 22 ± 5 years, mass = 66.2 ± 8.1 kg) were required to have at least 2 years of resistance training experience while lacking a history of asthma, lightheadedness, fainting, anaphylaxis, sickle cell traits, and other respiratory disorders. After a baseline 1RM test, subjects were paired by 1RM performance and gender, then randomly assigned in a counterbalanced treatment order to control (water) or ammonia trials after a minimum 72-hour recovery period for another 1RM test involving attempts at 100.0, 102.5, 105.0, and 107.5% of the established 1RM value. Testing was then repeated after the minimum rest period for the remaining trial. Results revealed the expected gender main effect for absolute deadlift 1RM (93.0 ± 29.5 [women]; 152.0 ± 29.5 kg [men]; p < 0.001), but no trial main effect (p = 0.874) or gender by trial interaction effect (baseline = 93.0 ± 15.3, 151.8 ± 42.3 kg; water = 92.0 ± 12.5, 150.9 ± 37.8 kg; ammonia = 92.5 ± 16.4, 153.4 ± 37.9 kg) for women and men, respectively (p = 0.559). Within the limitations of this study, there is no support for the practice of ammonia inhalation to improve deadlift 1RM in training or competition.

Introduction

Competitive powerlifting combines the maximal mass successfully lifted in a squat, bench press, and deadlift. Powerlifting is an international sport with the World Powerlifting Congress reporting 46 affiliate member countries (²⁷). The 2015 International and US Powerlifting Championship events reported more than 750 and almost 1,000 competitors, respectively (correspondence from Robert Keller, Secretary General, International Powerlifting Federation, March 9, 2016). Powerlifters, similar to athletes in other sports, seek ergogenic aids to gain an edge over their competitors. Several ergogenic aids used by powerlifters and other athletes such as anabolic-androgenic steroids, prohormones, human growth hormone, insulin-like growth factors, etc. have well-documented adverse health effects and/or provide an unfair competitive advantage (⁵). Other ergogenic aids appear to have little to no risk but also lack scientific evidence for an ergogenic effect (²¹). Evidence for the efficacy of any ergogenic aid used by athletes today ranges from a large body of scientific support to only anecdotal testimonials.

Although some ergogenic aids are banned in training and competition by the World Anti-Doping Agency, others, including ammonia inhalant (AI) use, are not banned and are used in competition by powerlifters (^16,26). In their international survey of powerlifters, Pritchard et al. (²²) revealed that 49% of all respondents used AI, 78% of users felt AI use was ergogenic, and 80% of all respondents indicated AI use was a safe practice. AI was typically used for 2–3 lifts during a competition (45% of AI users) and before the deadlift, the last event in powerlifting competitions. AI use by powerlifters is acknowledged by the International Powerlifting Federation Technical rules book (¹²), which states that “a lifter shall not … use ammonia within view of the public.” Physiological effects of AI include irritation of the nasal cavity and lungs resulting in momentary increased inspiration, respiration rate, and alertness (¹²). Perry et al. (¹⁹) reported increased middle cerebral artery blood flow velocity and increased heart rate after AI. The role of these physiological effects in improved powerlifting performance remains to be elucidated.

Despite the high prevalence of AI use by powerlifters, well-controlled research on the efficacy of AI use is almost nonexistent. AI was ineffective in increasing back squat and bench press repetitions at 85% of 1-repetition maximum (1RM) (²⁴) or maximal mid-thigh pull force, rate of force development, or electromyography activity (¹⁹), but increased Wingate test peak and mean anaerobic power was observed after a simulated American football game (²⁵). To our knowledge, no studies have examined the ergogenic effect of AI on the 1RM of any competitive weightlifting event. According to an international survey of powerlifters, 89% of AI use was associated with deadlift 1RM which is the last of 3 events in powerlifting competitions (²²). Therefore, the purpose of this study was to examine the effect of AI use on deadlift 1RM in college-aged male and female recreational weight lifters. We hypothesized that AI would significantly improve deadlift 1RM performance.

Methods

Experimental Approach to the Problem

For testing our hypothesis that AI would increase deadlift 1RM, we used a 2 gender × 3 treatment (baseline, water, and ammonia) design with repeated measures on treatment. The primary independent variable was treatment, with water and ammonia treatments administered in counterbalanced order after the baseline treatment. Subjects were blinded to their first assigned treatment of either water or ammonia up to the first exposure, after which they were aware of the treatment for subsequent deadlift 1RM attempts in that session and the remaining treatment in the third and final session. Therefore, the nature of the treatments precluded true blinding throughout the entire study. During the baseline session, absolute deadlift 1RM was measured after a standardized warm-up which was also used in the water and ammonia treatments. The following progressive approach was used to achieve deadlift 1RM in the water and ammonia treatments: 2 repetitions (reps) each at 65 and 75% of baseline 1RM; 1 rep each at 85, 90, and 95% of baseline 1RM; then 100, 102.5, 105 and 107.5% of baseline 1RM as necessary to failure. The study design attempted to mimic conditions during both training and competition, including attempts to lift the heaviest load in 3 attempts. Absolute deadlift 1RM was selected as the dependent variable for 3 reasons. First, the effects of AI are brief, therefore it is logical to assume that an ergogenic effect would occur within the much shorter time window of administration immediately before a 1RM attempt rather than before multiple high-intensity repetitions (²⁴). Secondly, the deadlift is generally considered to be a safe lift for recreational weight lifters assuming the use of proper technique. Finally, the deadlift is the last lift in powerlifting competitions and the lift most associated with AI inhalation among powerlifters (²²). The study protocol is presented in Table 1.

Table 1.: Study protocol.*

Subjects

Undergraduate exercise science majors (mean ± SD: n = 10 men; n = 10 women; age range = 19–34 years) were recruited from a strength and conditioning leadership course. All subjects were naive to AI use and were required to have a minimum of 2 years of resistance training experience, specifically experience with deadlift exercise. Data collection was done in the spring of 2016 beginning at the 10th week of the semester in order for one of the researchers to provide individual instruction on correct weight lifting movements including the deadlift. We used recreational athletes as subjects due to an insufficient number of available highly trained and competitive weight lifters. At the time of testing, all subjects had received supervised instruction on performing the deadlift and other weight lifting movements. Subjects were instructed not to change their weight lifting routines, nutritional intake, or hydration for the duration of the study and to refrain from any heavy lifting outside of the study. Otherwise, there was no control of periodization cycle training volume or intensity. Participants with a history of asthma, lightheadedness, fainting, anaphylaxis, sickle cell trait, and other respiratory disorders were excluded from the study. Ammonia inhalation has been reported to irritate the eyes and upper respiratory tracts in humans (²⁰) and rats (¹). This study used small amounts of inhalants 2 inches from the nose for a brief, split second inhalation. Subjects were only exposed a total of 6 times throughout the study with minimal duration and depth of exposure. All testing was conducted at one university. Before all testing, the study protocol was approved by the Human Subjects Institutional Review Board at Old Dominion University (Norfolk, VA). All procedures conformed to the Declaration of Helsinki as revised in 1996. Participants received a verbal explanation of the risks and benefits of the study and also provided written informed consent.

Procedures

Subjects reported for data collection on 3 separate sessions separated by 7 days. Baseline deadlift 1RM was measured in the first session after a standardized warm-up {fire hydrants (2 × 10 per leg); lunge stretches (2 × 10 seconds); dumbbell good mornings (2 × 10 at 4.5 and 9.1 kg [10 and 20 lbs]); 3 × 5 at 45% 1RM; and 2 × 3 at 50% 1RM} which was replicated in the other 2 sessions. Equipment used in the study included a standard Rogue Fitness (Columbus, OH) Echo Series Bumper Plates (1.1, 2.3, 4.5, 6.8, 11.4, 15.9, 20.4, and 25.0 kg [2.5, 5, 10, 15, 25, 35, 45, and 55 lbs] options) which were secured to a 20-kg (45-lb) Rouge Fitness (Columbus, OH) 28-MM Training Bar with spring collars. Deadlift 1RM testing took place on a standard 2.4 × 2.4-m (8 × 8-ft) Olympic regulation weightlifting platform (FW-147; ProMaxima, Houston, TX, USA), located in the university's student recreation center. Subjects were allowed to use any weightlifting accessories such as Olympic weight lifting shoes, belts, sleeves, etc., and were required to use the same equipment and the same grip and lifting technique for baseline, water, and ammonia trials. The AI was Pac-Kit (South Norwalk, CT, USA) AI medical kit refills (#9–100, 100 count). Each capsule contained 0.33-ml solution of ammonia (50 mg, 15%), denatured alcohol (35%), and water (50%). The control substance was water in an identical bottle.

For sessions 2 and 3, subjects inhaled the assigned inhalant in counterbalanced order and attempted to lift 102.5, 105, and 107.5% of the 1RM achieved in baseline testing. Subjects were asked to set their feet and adjust equipment (e.g., tighten belt, set straps, etc.) before the attempt, take in 1 maximal inhalation from the assigned bottle and perform the lift within 15 seconds of inhalation. Water (control) or ammonia capsules were placed in identical opaque plastic bottles along with a coin by an individual not involved with data collection or analysis. Immediately before administration, the bottle containing a subject's assigned treatment was shaken which broke the ammonia capsule by contact with the coin. The contents of the bottle (water or ammonia) were then inhaled through a small hole in the bottle cap. Subjects and the researchers were blinded to the treatments. If the subject failed an attempt, they were allowed a second attempt at the weight with identical procedures, including another inhalation of the prescribed inhalant. All subjects had a timed rest interval of 3 minutes between all attempts during this study for ideal recovery time without compromising performance (¹⁵). A given subject was measured at the same time of the day for baseline, water, and ammonia treatments which were separated by a 72-hour interval (Table 1). The trial-to-trial reliability of deadlift 1RM was determined by an intraclass reliability coefficient of 0.995 across 3 separate measurements.

Statistical Analyses

Baseline descriptive variables (age, baseline height and mass, and years of weight lifting experience) and 1RM data for baseline, water, and ammonia trials were examined for normality and homogeneity of variance. All variables conformed to Gaussian distributions according to the Shapiro-Wilk test. Differences between men and women for descriptive variables were examined by independent t test. The difference in the deadlift 1RM attempts between ammonia and water trials was examined by dependent t test. One-RM data and percentage changes between baseline, water, and ammonia treatments were analyzed by separate 2 gender × 3 treatment repeated-measures analyses of variance with Tukey post hoc comparisons for significant main and interaction effects. Repeated measures data conformed to sphericity assumptions according to Mauchly's test. All analyses were performed using IBM SPSS (Version 21; Armonk, NY, USA). The criterion for statistical significance was α = 0.05. Unless otherwise indicated, values are reported as mean ± SD.

Results

Ten men and 10 women completed all 3 testing sessions. Baseline characteristics are presented in Table 2. As expected, men were significantly heavier and had greater (p ≤ 0.05) absolute (kg) and mass-relative (kg·kg⁻¹) deadlift performance. There were no reported issues or injuries from participation in the study outside of normal soreness and delayed onset muscle soreness signs and symptoms. There was no difference between ammonia and water trials in deadlift 1RM attempts with the first attempt at 1RM measured at baseline (ammonia = 2.2 ± 1.2 vs. water = 2.1 ± 1.3, p = 0.629).

Table 2.: Baseline characteristics of study subjects.*†

Matching of subjects in pairs according to baseline performance and gender for randomized assignment to treatment order (water/ammonia; ammonia/water) resulted in no order effect (p = 0.533).

The effect of treatments on absolute deadlift performance is presented in Figure 1. As expected, there was a significant gender main effect (F_1,18 = 20.09, p < 0.0001) in favor of men. However, there was no trial main effect (F_2,36 = 0.135, p = 0.874) or gender-by-trial interaction effect (F_2,36 = 0.591, p = 0.559).

Figure 1.: Effect of baseline, water, and ammonia inhalation treatments on absolute deadlift 1-repetition maximum (1RM). Values are mean ± SE. Two gender × 3 trial design repeated measures analysis of variance. Gender main effect (p < 0.0001) with no treatment (p = 0.874) or gender × treatment interaction (p = 0.559) effects.

As shown in Figure 2, percentage changes in absolute deadlift strength (water vs. baseline; ammonia vs. baseline; ammonia vs. water) were not significantly different (F_2,36 = 0.141, p = 0.869) with no gender main effect (F_1,18 = 0.368, p = 0.552) or gender by percent comparison interaction effect (F_2,36 = 0.909, p = 0.412).

Figure 2.: Relative percentage changes in absolute deadlift 1-repetition maximum (1RM) between treatment pairs. Values are mean ± SE. Two gender × 3 treatment-pair design repeated measures analysis of variance. No gender (p = 0.552) or treatment-pair (p = 0.869) main effects or gender × treatment interaction (p = 0.412) effects.

Discussion

AI is commonly practiced by power athletes to induce heightened arousal and alertness, and increased respiratory rate (^16,26). AI use by powerlifters is most commonly associated with the deadlift which is the last lift in powerlifting competitions (²²). Despite the prevalence of this practice, there is scant research on the ergogenic effects of AI. Furthermore, we are unaware of any studies of AI ergogenic effects on maximal 1RM strength in any lifting task including the deadlift. The key finding of this study is that AI resulted in no significant difference in absolute deadlift 1RM after ammonia inhalation compared with either a water control or baseline measurement in male and female recreational weight lifters. Our null findings are similar to separate studies reporting no increase in mid-thigh pull force, rate of force development, or electromyographic (EMG) activity immediately, 15, 30, or 60 seconds after AI (¹⁹) and no effect of AI on back squat and bench press repetitions at 85% of 1RM (²⁴). To our knowledge, the only evidence of an AI ergogenic effect was an increase in Wingate test peak and mean power output after a simulated game of American football (²⁵).

This study did not examine a potential AI ergogenic mechanism. Cross-sectional survey data support a belief among users that AI increases psychological arousal and decreases perceived fatigue (²²). Middle cerebral artery blood flow velocity and heart rate have been reported to increase and peak 10 and 15 seconds, respectively, after AI (¹⁹). If any AI ergogenic mechanism is related to these acute changes, it is logical to surmise that the brief time window for effectiveness would be further reduced by International Powerlifting Federation (IPF) rules stating “a lifter shall not … use ammonia within view of the public” (¹²).

This study has several acknowledged limitations. We did not report mass-relative deadlift strength for baseline, water, and ammonia conditions since body mass was measured only before baseline measurement of 1RM. Although the subjects had the required weightlifting experience, they were recreational weight lifters with training goals that did not require knowledge of deadlift 1RM. As a result, the baseline condition was the first time that many had ever performed a deadlift 1RM. However, the absence of significant differences in deadlift 1RM between baseline and water or AI conditions supports the absence of a learning effect or any hypothesized AI treatment effect. Nevertheless, one recommendation for future study is to replicate this study in more experienced male and female powerlifters who represent more homogeneous populations where any AI ergogenic effect may be more apparent.

Equipment use was standardized within but not between subjects. Only one-third of the subjects used a weight-belt, which has been shown to improve lifting posture and stabilize the trunk by increasing intra-abdominal pressure (¹³) and rectus abdominis RMG activity (^9,17) while decreasing external oblique EMG activity (⁹). One subject used powerlifting straps which has been reported to retard the development of grip strength, an important contributor to successful barbell movements (²³). Differences in lifting technique (e.g., stances, grips, grip widths, etc.) within the standard of reaching full torso, hip, and knee extension while lifting the barbell from the floor could have affected any AI-related ergogenic effect on deadlift performance. Greater between-subject standardization in equipment use and technique would be expected in more experienced male and female powerlifters.

There was no tracking of the menstrual cycle in female subjects. Menstrual cycle phase has been reported to have no effect on maximal voluntary isometric contraction of knee extensors and flexors (¹⁸); first dorsal interosseus muscle (⁸), or isokinetic strength (¹⁰). On the other hand, greater knee extensor peak torque and isometric contractions of knee flexors have been reported at ovulation compared with luteal or follicular phases (³) and greater isometric lifting strength in the luteal phase than the follicular phase (⁶). Although any menstrual cycle-related fluctuations in muscle force production represents a maturation threat to internal validity in this study, female powerlifters compete in scheduled events without regard for menstrual cycle phase, a fact which supports the external validity of our study.

Another limitation to our study is the likelihood that true double-blinding did not occur throughout the entire protocol. It is possible that not all subjects were blinded after their first exposure to water or ammonia. Ammonia is a respiratory irritant, therefore a subject's reaction (or lack thereof) to ammonia or water undermine a completely blinded condition.

Previous studies have reported placebo effects associated with anabolic-androgenic steroid use of 9.5 (²) and 3.8% (¹⁴) in male weight lifters. In their review, Beedie and Foad (⁴) reported placebo effects ranging from −1.0 to 50.7% of baseline performance, with effects that were either statistically or clinically significant in all but one or 12 studies. The mean performances for ammonia, water, and baseline conditions are within a range of only 1.75 kg and not significantly different, which suggests no placebo effect.

Although ammonia is toxic in higher doses, AIs are used for the treatment of fainting. The single-dose ammonia concentration used in this study was the same as found in first aid kit capsules and is generally but not unanimously (⁷) considered as safe. Although the risk of adverse events related to AI use by athletes is low, a case study reported an allergic reaction after a single dose of aromatic AI in a female powerlifter who regularly used nonaromatic AI (¹¹). More frequent or even single low-dose exposure may cause pulmonary congestion and skin irritation in susceptible individuals (⁷).

In conclusion, AI use by powerlifters is acknowledged by the International Powerlifting Federation (¹²). AI use is prevalent among competitive powerlifters, usually before the deadlift (²²). We are aware of no prior study to test the effects of AI on 1RM for any weight lifting movement. The prevalence of AI use by competitive powerlifters suggests a possible ergogenic effect of AI use on deadlift 1RM. However, within the previously discussed limitations of this study, there was no significant increase in deadlift performance after AI use.

Practical Applications

Although AI use is prevalent among certain strength and power athletes, the ergogenic effects of its use on weightlifting performance has received little research attention. This study reported no improvement in deadlift 1RM after AI. Based on this finding, there is no rationale to recommended AI use to strength and power athletes for improved deadlift performance.