Strongman training has become an increasingly popular modality used by practitioners for athletic development and general strength and conditioning. In a recent survey of strength and conditioning coaches, 88% (n = 220) reported using strongman equipment in the training of their athletes and 81% reported good to excellent results from using ST (38). Strongman training and competition involve large multijoint movements that share similar kinematic profiles to common strength training exercises (RST) such as the squat and deadlift (36,37). Common strongman exercises include sled pulls, farmer's walks, tire flips, and overhead presses (40). A key difference between strongman exercises and RST is that strongman exercises are often performed in a horizontal plane and involve a moving component where an athlete performs carries, pushes, or pulls of an object from 1 location to the next (39). On a physiological level, this may elicit unique metabolic and hormonal responses to those of RST.
Current research pertaining to ST (either of an exercise or a training session) reports acute increases in metabolic outputs across a variety of different measures. Blood lactate (1,20,35), heart rate (1,20,22), and oxygen consumption (1) increased after a session involving a single strongman type exercise. Research investigating hormone levels and ST has shown an increase in acute hormonal levels of testosterone after an ST session training (12,35). Likewise, cortisol increases acutely after ST before falling below baseline levels at around three hours after ST (35).
Current research on physiological response to RST report increases in acute metabolic measures of blood lactate (7,21,34), heart rate (2,11,26), and oxygen consumption (11,26,30). The RST has also been reported to induce large hormonal elevations with acute increases in testosterone (12,29,33) and cortisol (5,8,14). The reader is referred to a recent review on the physiology of ST in which direct comparison between acute responses to ST sessions and traditional strength training sessions is elaborated (41).
Although research by Ghigiarelli et al. (12) has examined the testosterone response to an entire ST session and compared it with that of hypertrophy training, no research has collectively examined the metabolic and hormonal effects of ST and compared it directly to RST. Therefore, the aim of this study was to examine the acute metabolic and hormonal response to ST and compare it with RST regarding overall session profile. This information on ST could be used to give exercise professionals a deeper insight into the physiological mechanisms involved in strongman and its potential adaptations in performance and body composition.
Experimental Approach to the Problem
All participants acted as their own control in a crossover design in which participants performed both a ST session and a traditional RST session within 7 days apart. Five participants performed ST first and 5 performed RST first, and sessions were equated for approximate total set duration. Testing was conducted at the same time each day, and participants were required to perform each session with identical presession routines such as nutrition, exercise, and sleep. Variables of interest included salivary testosterone, blood lactate, heart rate, calorie, fat, and carbohydrate expenditures. Analyses were conducted to determine differences in physiological responses within and between the 2 different protocols.
Ten healthy men (23.6 ± 7.5 years; 85.8 ± 10.3 kg) volunteered to participate in this study. All participants had been regularly resistance training for at least the immediately previous 2 years, and a squat and deadlift strength of at least 1.0 and 1.2 times body mass, respectively. Typical training frequency for the participants varied from 3–6 days of structured resistance training per week with between 6 and 10 repetitions for 2–4 sets for compound movements. Almost all participants were from a strength training facility where small group sessions were common, and training prescribed; hence, recent training practices were very similar for all. No participants had professional strongman competition experience, but 2 participants had competed in a novice strongman competition. All participants were familiar with and had performed the strongman exercises in their own training. Participants were required to be between the ages of 18–45 and experienced with the squat, bench, deadlift, and power clean exercises. Participants had no existing injuries that could be aggravated by doing the ST and RST sessions, and were not taking any performance enhancing drugs. The study was granted Institutional ethical approval, and all participants signed a voluntary informed consent form before participating.
1 Repetition Maximum Testing
Given participants were experienced strength trained individuals, maximal strength (1 repetition maximum [1RM]) for the RST exercises was determined by calculation ([rep weight × number of reps × 0.3333] + rep weight) (8) based on very recent training load history (Table 1).
All sessions were supervised by a New Zealand Registered Exercise Professional (NZ REPs). All sessions were conducted within the institutional strength laboratory. For both sessions, participants first conducted a warm-up consisting of 5 minutes on a stationary bike (Life Fitness, New Zealand) at self-selected intensities with the aim of getting heart rate to 110–120 b·min−1 followed by 3 minutes of dynamic stretching involving leg swings, arm swings, walking lunges, and squats with minimal added load. Participants were then fitted with a mask attached to a breath-by-breath gas analyzer (Metalyzer 3Bsystem; CORTEX Biophysik GmbH, Leipzig, Germany) and a heart rate monitor (Polar, Finland) before commencing the session (Figure 1).
Traditional Strength Exercise Training Session
Participants performed the squat, deadlift, bench press, and power clean in that order with a 3-minute passive rest interval between sets and exercises. Participants were required to perform 2 warm-up sets at 50% and 75% of the working set which was at 75% of their predicted 1RM load, for 10 repetitions. Participants were instructed to complete the repetitions at a self-selected pace. Sets at this intensity and duration typically involved approximately 30 seconds of total time per set. Participants were fitted with the oxygen facemask and cart, which was positioned in a way to allow the unrestricted exercise performance (Figure 2).
For the squat, participants were required to remove the bar from the racks with the bar positioned across the middle of the trapezius and squat down until the bottom of the thigh was parallel with the ground. For the deadlift, the participants were required to lift the bar from the floor, and the bar had to touch the ground between every rep; the “touch and go” protocol was permitted, but excessive bouncing was not. In the bench press, participants were required to lower the bar down until it touches their chest and then press it up to full arm extension. The power clean (Figure 3) exercise required participants to pull the bar from the ground to their clavicle using a triple extension motion, a touch and go protocol was permitted with no excessive bouncing. During familiarization, testing loads were adjusted so that set duration was always between 28 and 32 seconds duration.
Strongman Training Session
The oxygen cart was positioned or wheeled alongside participants as they performed the exercises (Figures 4 and 5). The exercise order was sled drag, farmer's walk, 1 arm dumbbell clean and press, and tire flip. Participants were required to perform 2 warm-up sets of 50% and 75% of the working set; the working set for sled drag was 200% of body weight for 12 m, farmer's walk 80% of body weight in each hand for 24 m, and dumbbell overhead at 30% of body weight for 10 repetitions. For the tire flip, 2 sets of a sumo stance deadlift at approximately 50 and 75%1RM were used as a warm-up, given only the full-sized tire was available. For the tire flip, all participants performed 1 set of as many repetitions as they could in 30 seconds on a 220-kg tractor tire (external diameter 150 cm, height on ground 80 cm). These percentages originated from pilot testing using 4 participants who performed sets of the strongman exercises at different percentages of body weight with the goal of ensuring sets would be approximately 30 seconds in duration, in an effort to approximately equate the 2 session protocols. There was 3-minute passive rest between all sets and exercises. In all sets, participants were instructed to perform at a self-selected pace but with maximum effort.
For the sled drag (Figure 4), participants were attached to a harness with the sled positioned behind them. They started in the 4 point power position and took steps forward, instructed to stay low for the whole set (within hand touching distance of the ground), and not were permitted to come upright into a sprint position. The instruction issued was to go as fast as possible. The drag was continued for a timed 30-second period.
For the farmer's walk, participants deadlifted a pair of farmer's handles (length 1,300 mm, handle width 30 mm) off the floor and taking short steps walked 12 m before placing the farmer's bars back down, and they then turned and picked up the handles again carrying them back to the start position. The instruction issued was to go as fast as possible. Partial repeats of this “lap” were continued if needed until a 30-second set duration was met.
For the dumbbell, overhead participants were permitted to get the dumbbell overhead anyway they chose to and were allowed 2 hands to clean the dumbbell but only 1 hand to put the dumbbell overhead, standard technique being a 2 hand clean followed by a 1 arm push press; however, some participants chose to snatch the dumbbell. Repetition cadence was self-selected. At each repetition, the dumbbell was returned to the floor and finished when participants had completed a timed 30-second set, typically approximately 10 repetitions to full extension (10 ± 1.3 repetitions). Participants were permitted to alternate arms or complete all repetitions on 1 arm based on their personal preference.
The tire flip (Figure 5) was performed for a single repetition at a time with maximum effort, and participants ran 180° around the tire to flip it back to the starting position. At each flip, the participant assumed a deep squat position leaning their chest into the tire with their hands hooked underneath the tire. Participants performed triple extension of the ankles, knees, and hips bringing the tire up to chest height; their hands then transitioned from under the tire to a push position, and they drove the tire forward completing the flip. The instruction was to complete as many flips as possible in 30 seconds.
Participants were instructed to abstain from brushing their teeth or drinking hot liquid for 30–60 minutes before testing. All saliva collections were made with participants seated, leaning forward, and with their heads tilted down. Participants were instructed to swallow to empty their mouth of saliva before an unstimulated whole saliva sample was collected into a sterile bijou tube (7 ml capacity with screw top, Labserve, Auckland, NZ). Care was taken to allow saliva to dribble into the collection vial with minimal orofacial movement. Samples were frozen and stored at −80° C until analysis. The salivary testosterone concentrations were determined using commercially available ELISA kits (Salimetrics, State College, PA, USA). The sensitivity of the kits was <1.9 pg·ml−1 (salivary testosterone). The mean intra-assay coefficient of variation was 2.7%.
Whole blood was taken by fingertip puncture using a spring loadable lancet (Safe-T-Pro Plus, Germany), and blood was taken and measured immediately using a Lactate Pro (Lactate pro, Arkray, Japan) lactate analysis unit.
Heart rate was recorded using a heart rate strap and watch (Polar, Finland). Heart rate was recorded 15 seconds before every set and immediately post. After the session, heart rate was recorded every 30 seconds for 20 minutes; it was then recorded every 5 minutes for the next hour.
Energy Expenditure and Oxygen Consumption
Energy expenditure and gas exchange was measured using breath-by-breath gas analysis, which was calibrated at the start of every testing day. The mask was fitted to the participants after the standardized warm-up and remained on and recording data for each session and 80 minutes after workout during a passive postsession recovery data collection period termed STrecov and RSTrecov for post-ST and post-RST, respectively. Immediately after session, participants were allowed to lift the mask up to expel saliva for the second saliva reading and have a brief drink of water before refitting the mask and commencing the STrecov or RSTrecov data collection phase. The gas analysis was used to determine minute ventilation, O2 consumption, and CO2 production. Gas sampling allowed for estimation of fat and carbohydrate oxidation and also energy expenditure using stoichiometric equations.
Descriptive statistics (mean ± SD) were calculated for all dependant variables that followed a normal distribution. The data were screened for normality using a histogram plot and Shapiro-Wilks test. Normally distributed data were analyzed using a paired sample T-test with significance set of p ≤ 0.05. Data that did not follow a normal distribution were analyzed using the Wilcoxon signed-rank test and were presented using the median, upper, and lower quartiles, minimum and maximum values. To avoid type I and type II errors due to multiple pairwise comparisons, the alpha level was adjusted to p ≤ 0.025 when 2 comparisons were conducted and p ≤ 0.0125 when 4 pairwise comparisons were made. All statistical analyses were performed using SPSS software (version 22, SPSS Inc., Chicago, IL, USA).
There were no significant differences (p = 0.742) in set times among protocols; mean set time for ST was 29 ± 4 seconds, whereas RST was 29 ± 2 seconds. Session rate of perceived exertion was 13 for both ST and RST with no significant differences (p = 0.103) between sessions. Table 2 presents median values for the measured variables across all time points.
Figures 6–9 present heart rate, caloric, fat, and carbohydrate expenditures for the resting period (median of 30 minutes passive rest on a separate day), ST and RST (median of the whole training session from the first work set to the last work set including rest periods between sets), and STrecov and RSTrecov (median for the 80-minute passive recovery period immediately after the training sessions). Presented are the median, upper, and lower quartiles, and minimum and maximum values for each variable. Also, presented are p values for comparison within and between sessions.
Heart rate, caloric, carbohydrate, and fat expenditures were significantly greater for both ST and RST than resting.
Heart rate was significantly higher in both STrecov and RSTrecov than resting. Calorie and carbohydrate expenditures were not significantly different in STrecov and RSTrecov compared with resting. Fat expenditure was significantly greater in RSTrecov when compared with resting, whereas STrecov not significantly different from resting.
Figures 10 and 11 present testosterone and lactate responses to the 2 different protocols from pre to immediately post session. Presented are the median, upper, and lower quartiles, and minimum and maximum values with associated p value for within-group and between-group differences. Lactate increased significantly from pre-to-post ST and RST, but testosterone did not.
The aim of this study was to compare ST and RST that had been equated for approximate total set time and session duration for their respective acute physiological responses. This study was the first to examine collectively the metabolic and hormonal response to ST and compare it with RST training. We found that ST and RST type training produced similar acute metabolic and hormonal responses. Winwood et al. (39) investigated the long-term training effects of strongman exercises on aspects of muscular function and performance and compared it with traditional training. No significant differences on the changes in muscular performance measures between the ST group and the traditional training group were found. We conjecture that the acute physiological responses in our study may be indicative of the mechanisms underpinning the adaptations observed by Winwood et al. (39).
It was surprising to see that neither group in our study experienced a significant acute increase in testosterone at any time point analyzed. Although the majority of research has found testosterone rises acutely after resistance exercise and ST (5,12,15,28,32,33), some research has demonstrated that testosterone can decrease after resistance training (3,23). In the resistance training studies in which no acute increase in testosterone was reported, it has been speculated that lower volume training programs are responsible for the apparent insufficient stimulus (5,15). It is, therefore, possible that the protocols used in our study did not provide sufficient volume to induce a significant increase in testosterone levels. Our study used 2 warm-up sets and 1 working set at 75% of 1RM for 10 repetitions over 4 different exercises with 3-minute rest between exercises equating to 40 total working repetitions at 75% of 1RM. Previous research reported testosterone to increase using a hypertrophy protocol, which equated to 100 working repetitions at 75% of 1RM (10 sets of 10 repetitions, 2-minute rest between sets), whereas a power protocol and strength protocol did not evoke any changes in testosterone with volumes of 48 repetitions at 45% of 1RM (8 sets of 6 repetitions, 3-minute rest between sets) and 24 repetitions at 88% of 1RM (6 sets of 4 repetitions, 4-minute rest between sets) for power and strength, respectively (5). Other research also demonstrated an increase in testosterone using 100 working repetitions at 70% of 1RM (10 sets of 10 repetitions, 3-minute rest between sets), whereas their second loading scheme of 20 repetitions at 100% of 1RM with 3-minute rest experienced no change (15). Although our loading scheme was similar in intensity to loading schemes, which produced significant increases in testosterone, it appears to lack the volume used in the studies reporting significant increases, further supporting the influence of training volume on the acute testosterone response.
Median heart rates (69% max heart rate for both protocols) reported in this study fell within the moderate range defined by the ACSM (between 64% and 76% of heart rate max) (10) indicating that both protocols could provide the stimulus required to achieve a positive adaptation in cardiovascular conditioning. This is consistent with the findings of Hrubeniuk et al. (18), where resistance training was reported to be a sufficient method of reaching the aerobic component of the physical activity guidelines and a suitable alternative to traditional aerobic training methods. Keogh et al. (20) found heart rates of 92% of maximum after 2 sets of 6 tire flips with 3-minute rest between, whereas Berning et al. (1) reported a mean heart rate of 96% of maximum after 400 m of car push and pull. Comparatively, we found slightly lower heart rates after the final set of each exercise (81–83% heart rate max) likely because of the difference in our loads selected to equate the 2 training modalities. Bloomer et al. (2) reported heart rates of 82% of maximum after 30 minutes of intermittent free weight squatting, slightly higher than the median heart rate of 69% of max in this study; however, the protocol used by Bloomer et al. (2) had shorter rest periods of 60–90 seconds.
Caloric expenditure in this study is consistent with the findings of Falcone et al. (9) who reported resistance exercise at 75% of 1RM to expend an average of 8.8 kcal·min−1 when performed across 6 different exercises from a total session time of 30 minutes, whereas we reported median values of 8.9 and 9.1 kcal·min−1 for ST and RST, respectively. Our findings on RST are similar to those of Ratamess et al. (26) who reported 8.2 kcal·min−1 after sets (∼37 seconds) of barbell back squats and 7.8 kcal·min−1 after sets (∼30 seconds) of deadlifts, both at 75%1RM. These findings, and ours, demonstrate the relative equivalency in total energy expenditure of resistance training sessions using large muscle group compound exercises with cardiovascular conditioning exercises such as treadmill running. Falcone et al. (9), for example, reported treadmill running at 70% of max heart rate for 30 minutes to expend an average of 9.5 kcal·min−1, very similar to our findings. Hence, our findings provide support for the inclusion of either ST or RST in programs designed to elicit the calorie expenditure considered necessary to support objectives such as weight loss (16).
Fat expenditure has been found to be inversely correlated with exercise intensity (4); this study observed that fat expenditure was not significantly elevated during either ST or RST. The RST performed for sets and repetitions in our study is considered a form of high-intensity exercise (9), these findings support such a view and suggest that ST may be considered high intensity. Carbohydrate expenditure was significantly elevated during both ST and RST when compared with resting, and this is consistent with other research on high-intensity exercise, which has demonstrated that it is primarily fueled by glycogen (9). Carbohydrate expenditure has been shown to increase as exercise intensity increases (27). Large increases in carbohydrate expenditure demonstrate the high-intensity nature of ST and RST.
In the recovery period after exercise, the oxygen consumption is commonly termed the excess postexercise oxygen consumption (EPOC) (6). The EPOC represents the number of calories used above baseline after exercise, and the effect is greater immediately after exercise and decreases with time (6). Researchers have demonstrated increases in energy expenditure and EPOC after resistance training (24,31). This study reported an increase in energy expenditure after both ST and RST; however, they were not significantly different from resting. Research pertaining to EPOC and resistance training has demonstrated training volume (13), intensity (19), and rest intervals (17) to have the largest effect on the magnitude of the EPOC. In our study, rest periods and loads were chosen as they fell within the recommended guidelines to increase both hypertrophy (29) and strength (30), and could be approximated in both ST and RST. The lack of significant differences in EPOC among ST, RST, and baseline is likely due to a combination of insufficient volume, intensity, and rest intervals that were too long to elevate EPOC greatly. Although our study has demonstrated no significant differences between STrecov and RSTrecov compared with baseline, greater volumes and intensities would likely affect the magnitude of the EPOC, rest times could also be shortened to 60–90 seconds while still keeping within the hypertrophy training recommendations (29).
Researchers have theorized that fat oxidation is enhanced during recovery from resistance exercise to spare available carbohydrate for glycogen resynthesis, and to replenish muscle glycogen, fat expenditure must be enhanced (25). Our findings support this theory for RST, as in RSTrecov, fat was significantly elevated while carbohydrate was not; however, in STrecov, neither fat nor carbohydrate expenditure was significantly elevated. In conclusion, the results of this study indicate that the acute physiological responses to ST and RST do not differ significantly when performed for the same total set duration.
This study supports the view that ST can be effective at evoking similar acute physiological responses to those of RST. Our findings have practical implications for exercise prescription for both general population and athletes. Practitioners looking to prescribe exercise programs can arguably expect similar metabolic adaptations, given the observed similarities in session response between the 2 protocols we examined. Strongman training or RST could elicit cardiovascular adaptations in addition to the expected metabolic adaptations commonly associated with resistance training, given heart rates for both protocols fell within the moderate level as defined by the ACSM (10). Strongman training or RST can be used to increase energy expenditure and, in turn, the energy deficit necessary for weight loss (16).
The authors would also like to thank and express their appreciation for all participants and assistants for their time and effort in volunteering to take part in the research. The authors disclose no professional relationships with companies or manufacturers who will benefit from this study. The results of this study do not constitute endorsement of the product by the authors or the National Strength and Conditioning association.
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