Assessing the effect of psychological priming techniques on salivary hormones and physical performance markers

Testosterone and cortisol have contrasting anabolic and catabolic effects on the musculoskeletal system and altering effects on metabolism and psychological behavior. A literature review was undertaken as part of this thesis to synthesize current research on these hormones' production, regulation, and effects. Testosterone is a potent, naturally secreted androgenic anabolic hormone essential for muscle growth through protein synthesis, inhibiting muscular breakdown, altering muscular strength, metabolic regulation, and behavioral modulation through altered motivation and risk-taking. Cortisol is essential for producing energy due to a stress response from hypoglycemia, exercise, or a fight-or-flight response, and is also essential in the process of muscular hypertrophy. It is also a modulator of status-relevant behavior due to the dual-hormone hypothesis with testosterone. This hypothesis states that the relationship between these two hormones is cyclical, with either hormone inhibiting the others’ effects when their concentration levels are high; for strength and conditioning coaches, understanding these hormones is critical for effective training programming.

The potentiation of testosterone through methods such as listening to music or performing physical movements prior to undertaking an athletic endeavor is known as priming. Potentially, when an individual is primed, their performance level could improve due to higher levels of motivation and risk-taking. However, a protocol to achieve this potentiation similar to a physical warm-up protocol is lacking. Therefore, a systematic review and meta-analysis were completed as part of this thesis to examine the current body of literature pertaining to the priming of testosterone before undertaking a physical performance test. Findings showed that testosterone could be primed, which subsequently improved physical performance markers.

Five peer-reviewed articles with 147 subjects met the inclusion criteria relating to testosterone priming in the defined sporting context. The findings of this systematic review and meta-analysis indicate that the viewing of a positive video clip in the presence of a smaller stranger significantly (p < 0.05) raises testosterone by 50% (g = 2.90, 95% confidence intervals (CI) 2.56, 3.23), a bigger stranger by 21% (g = 1.00, 95% CI 0.75, 1.25), a bigger friend by 20% (g = 1.10 95% CI 0.85, 1.35), and a smaller friend by 8% (g = 0.49, 95% CI 0.26, 0.73). Similar was found when viewing alone a positive video clip by 11% (g = 0.88, 95% CI 0.64, 1.12) or a successful short video clip by 12% (g = 0.87, 95% CI 0.62, 3 1.11) and being in the presence an attractive female observer by 39% (g = 0.67, 95% CI 0.61, 0.72). Finally, increased testosterone improved performance makers in skateboard tricks, rugby performance, a three-repetition maximum back squat (3RM), and bench press. On the contrary, aggressive video clips gave mixed results: testosterone rose by 10% (g = 0.67, 95% CI 0.43, 0.90) prior to performing a 3RM squat, with only a trivial finding of 1% (g = 0.03, 95% CI -0.20, 0.26) in men and -10% (g = -0.36, 95% CI -0.56, -0.16) in women before measuring hand grip strength and countermovement jump (CMJ) height. Additionally, the results highlighted a need for more literature regarding testosterone priming. Most primers implemented were video clips, with only one other stimulus recorded in this review, which was the presence of a female observer. Therefore, a wide range of priming techniques and subjects are required to add to the limited data already collected.

Due to the small number of studies found, the aim of Study 1 was to examine the frequency and modes of psychological priming techniques and strategies currently being implemented by athletes of various performance levels. A 15-question, anonymous survey was developed and shared via social media. Ninety subjects met the inclusion criteria, which were made up of 11 professional, 17 semi-professional, and 54 amateur-level athletes, with seven not competing. Priming strategies were implemented by 79% of subjects without using a coach, 10% used strategies with their coach, and 11% did not prime. For athletes, music was the preferred choice (27%), followed by instructional self-talk (24%), motivational self-talk (23%), applied physical actions (20%), and watching video clips (6.3%). For athletes that implemented a priming strategy via a coach, their preferred technique was motivational statements, with 55% implementing this technique, followed by 27% utilizing inspiring team talks, and only 18% playing music. Of those implementing a priming strategy, 66% found them to be either “very” or “extremely effective.” 38% of subjects felt priming accomplished this through increased motivation, 22% felt it reduced their fear and anxiety, 21% thought it improved their intensity, 15% felt it increased strength and power, and 2% thought it improved endurance. The chi-square test also found a significant (ϕc = 0.27; p = 0.011) relationship with using priming to increase motivation. These results demonstrate that priming strategies are being used irrespective of coach intervention; therefore, educating coaches and athletes on implementing priming techniques has its place when aiming to improve athlete performance.

Study 2 built on the results of the systematic review and meta-analysis, and Study 1, by investigating the priming effect of listening to self-selected music (SSM) or implementing motivational self-talk with imagery (MSTI) prior to performing a maximal strength 3RM back squat. Endocrine markers of salivary testosterone and cortisol concentrations were investigated to identify whether either strategy invoked a change in their concentration levels to explain the mechanisms at work should differences in 3RM across interventions be noted. Due to the COVID-19 pandemic, participation numbers for the following studies were affected. As a result, fifteen healthy collegiate adult subjects with a mean age of 22.5 ± 5.8 years, 173.5 ± 8.2 centimeters (cm) tall, and a mass of 71.7 ± 9.2 kilograms (kg) undertook the test. A repeated measures ANOVA revealed no statistically significant differences in 3RM, testosterone, or cortisol markers in SSM or MSTI groups. However, using Hedges g effect size analysis, there were small increases in 3RM back squat performance in MSTI and SSM conditions (g = 0.22, 95% CI -0.10, 0.54, and g = 0.26, 95% CI -0.23, 0.75 respectively) compared to a control (CON). SSM and MSTI increased testosterone levels compared to CON (g = 0.66, 5% CI -0.06, 1.37 and g = 0.39, 95% CI -0.27, 1.06, respectively), while trivial changes were observed in cortisol levels. Therefore, a small practical difference occurred in the testosterone: cortisol (TC) ratio in MSTI and SSM (g = 0.23, 95% CI -0.41, 0.87 and g = 0.31, 95% CI -0.34, 0.96 respectively). In summary, strategies such as SSM and MSTI may prime a healthy adult’s performance during training sessions, such that they can increase training intensity; this may be due to increases in testosterone and its potential effect on motivation and risk-taking.

As a result of motivational self-talk (MST) and SSM recording a small effect size increase in the 3RM back squat, the third study investigated the effect of these priming techniques on an upper body performance marker. A bench press exercise was implemented for four sets of four repetitions (reps) at a four-repetition maximum (4RM) intensity. Endocrine markers of salivary testosterone and cortisol concentrations were investigated to identify whether either strategy invoked a change in their concentration levels to explain the mechanisms at work should differences in the four sets of four repetitions across the interventions be noted. Twenty-one healthy collegiate adults with a mean age of 23.0 ± 3.5 years, 176.2 ± 3.9 cm tall, and a mass of 75.3 ± 9.0 kg participated in this study. No statistically significant differences across interventions were found in the 4RM, cortisol, and testosterone markers. Using Hedges g effect size, trivial differences in volume load lifted against CON in SSM and MST were found (g = 0.09, 95% CI -0.42, 0.59, and g = 0.06, 95% CI -0.45, 0.57, respectively). Average barbell velocity demonstrated a trivial increase when comparing MST to CON (g = 0.15, 95% CI -0.36, 0.65), but a trivial decrease when SSM (g = -0.14, 95% CI -0.65, 0.37) was implemented. Salivary testosterone concentration levels incurred a large increase after MST (g = 1.04, 95% CI 0.50, 1.58) and SSM (g = 0.85, 95% CI 0.32, 1.38) interventions. Salivary cortisol concentrations produced moderate changes after SSM and MST conditions (g = 0.81, 95% CI 0.28, 1.34, and g = 0.78, 95% CI 0.25, 1.30, respectively). In summary, no statistically significant results were found. However, meaningful, practical differences were found with the volume of load lifted increasing over the four sets by 31.26 kg and 21.56 kg in SSM and MST, respectively. Therefore, these changes could potentially equate to notable differences over time, with increased testosterone concentration levels potentially driving small load increases.

Research has noted that physical performance markers can improve when being observed. As athletes are observed during performances, Study 4 investigated the observer effect of being viewed in person (OE). Additionally, in recent years, social media has grown in popularity; therefore, being observed virtually via social media (SMO) was also investigated. While warming up, subjects were observed, salivary testosterone and cortisol concentration levels and a subsequent 65% 1RM back squat exercise to repetition failure were tested to assess whether these primers affect a muscular endurance marker as no statistically significant results had been reported in the maximal strength performance markers. Additionally, being primed may assist in pushing through the “muscular burn” felt when performing muscular endurance repetitions rather than maximal strength repetitions. Back squat reps and bar velocity (m/s) were measured, along with the endocrine salivary concentration levels and their ratios. No statistically significant results were found across twelve healthy collegiate adult subjects with a mean age of 22.4 ± 2.9 years,175.0 ± 5.2 cm tall, and a mass of 76.6 ± 7.0 kg. However, using Hedges g effect size, practical differences were noted. A moderate increase in testosterone in SMO (g = 0.79, 95% CI -0.12, 1.46) was recorded, but only a trivial difference in OE (g = 0.06, 95% CI -0.58, 0.71) compared to CON. The SMO condition produced a lower cortisol rise (g = 0.09, 95% CI -0.56, 0.73) than OE (g = 0.22, 95% CI -0.43, 0.87) and CON. As a result, the TC ratio noted a moderate change in SMO (g = 0.58, 95% CI -0.08, 1.24) and OE (g = 0.10, 95% CI -0.55, 0.74) compared to CON. The SMO condition produced the most reps performed at 17.50 ± 6.14 reps (g = 0.43, 95% CI -0.22, 1.08), OE 17.33 ± 6.72 reps (g = 0.38, 95% CI -0.27, 1.03) compared to CON 14.83 ± 5.19 reps. With a small increase in mean bar velocity in both interventions, SMO = 0.49 m/s (g = 0.27, 95% CI -0.37, 0.92) and OE = 0.49 m/s (g = 0.28, 95% CI -0.37, 0.92) compared to CON = 0.47 m/s. In summary, no statistically significant differences were noted. However, practical differences were. Filming subjects for social media appears to have a greater effect on back squat bar velocity and completed repetitions, along with a higher testosterone and TC ratio than the control and the observer effect. Therefore, performance levels may improve if implemented throughout a training program.

The final study sought to investigate the priming effect of listening to SSM, implementing MSTI, and being observed through SMO before performing a muscle endurance sixteen-repetition maximum back squat (16RM). The barbell average velocity was recorded throughout the back squat, and prior to this, isometric mid-thigh pull (IMTP) and a CMJ were measured. Endocrine markers of salivary testosterone and cortisol concentrations were also taken to investigate the possible underpinning psychophysiological mechanisms at work. Twenty-eight healthy collegiate subjects with a mean age of 28.9 ± 8.0 years, 167.7 ± 34.8 cm tall, and a mass of 78.3 ± 12.5 kg partook in the study. Due to subject availability, not all subjects performed all interventions. Therefore, individual intervention results were measured alongside subjects who completed all three interventions (Trio). Results revealed a significant increase in load lifted in SSM 65.07 ± 5.09 kg (g = 0.55, 95% CI -0.12, 0.99, p < 0.001) vs. CON 50.00 ± 4.42 kg, MSTI 61.14 ± 6.45 kg (g = 0.56, 95% CI -0.12, 1.00, p = 0.007) vs. CON 48.57 ± 4.76 kg and SMO 59.14 ± 5.86 kg (g = 0.55, 95% CI -0.08, 1.01, p = 0.01) vs. CON 47.86 ± 4.80 kg. The Trio group also recorded statistically significant results in SSM 68.10 ± 6.64 kg (g = 0.85, 95% CI -0.05, 1.74, p = 0.001), and MSTI 64.50 ± 8.21 kg (g = 0.60, 95% CI -0.52, 1.72, p = 0.02) vs. CON 50.00 ± 5.73 kg, but not SMO 59.50 ± 7.87 kg (g = 0.40, 95% CI -0.82, 1.63). All other markers and tests did not produce significant changes except for a reduction in peak power during the CMJ in the MSTI intervention (p = 0.04, g = -0.23, 95% CI -0.73, -0.23 (3661.86 ± 277.07 W) compared to control (4307.21 ± 284.66 W)). Moderate to large effect size reductions occurred in cortisol levels in the Trio group (ST g = -0.98, 95% CI -1.98, 0.01 (82%)), with SSM and SMO noting moderate changes (g = -0.68, 95% CI -1.68, 0.32 (93%) and g = -0.67, 95% CI -1.42, 0.09, (88%), respectively) vs. CON (131%). Testosterone levels did not produce any notable changes. In summary, SSM, MSTI, and SMO may prime a healthy adult’s performance for muscular endurance exercises but not for maximal strength and power during training sessions. Improvements may result from cortisol concentration levels reducing, as cortisol moderates the effect of testosterone and its subsequent impact on motivation and risk-taking behavior changes.

In conclusion, the findings from this thesis suggest that i) healthy adults are already innately implementing priming techniques to improve performance through listening to music and motivational self-talk and physical actions; ii) priming can improve muscular strength and endurance performances but not maximal muscular strength and power in healthy adults; iii) the underpinning mechanisms for this effect may potentially be the rise in testosterone to increase motivation and subsequent risk-taking to increase the load placed on the barbell to lift more than they initially thought was possible. Simultaneously, the modulation of cortisol to increase the TC ratio appears equally important due to the hormones working in tandem. Further research is required to understand the efficacy of priming more fully.