Strongman exercises are becoming more prevalent in fitness centers and training facilities, likely owing to the novelty and competitive nature of the exercises. Despite this increased interest, current research on the physiological responses to strongman training has only examined acute responses, with much of this involving only a single exercise. The aim of this narrative review was to gain a better understanding of the existing research on strongman training by comparing physiological responses to strongman and weight training modalities.
COMMON STRONGMAN EXERCISES
In a recent survey of 220 strength and conditioning coaches, 88% reported using strongman implements in the training of their athletes. The strength and conditioning coaches surveyed trained athletes ranging from amateur (n = 74), semiprofessional (n = 38), and professional level (n = 108) and included coaches from organizations such as the National Football League (NFL), National Rugby League, Super Rugby, National Basketball Association, and Major League Baseball (39). In the survey, strongman implements were defined as “any non-traditional implement integrated into strength and conditioning practice” and the main implements used were sleds, ropes, kettlebells, tires, sandbags, and farmers' walk bars.
In strongman competitions, the truck pull is a common event and involves an athlete pulling a truck using a harness attachment connecting the athlete to the truck. The athlete faces the same direction they wish to pull toward, with the truck attached behind them by a chest-mounted harness. Adopting the 4-point power position with both hands and feet on the ground they use lower-body strength to take steps forward pulling the truck. Although the truck pull is often used in strongman competitions, it is impractical for athletes and coaches to implement a truck pull in regular training because of space requirements, thus a sled with a chest harness (Figure 1) is often used to simulate the truck.
The farmers' walk involves an athlete deadlifting 2 farmers' bar handles (ostensibly, long dumbbells with raised handles; Figure 2A and 2B) on either side of them and then walking while carrying these loads, usually for a set time or distance with a set weight in competition settings. The farmers' walk is believed to require high levels of grip strength, core strength, and upper back strength (24), as well as the ability to walk quickly under substantial load (44).
The tire flip involves athletes flipping large truck or tractor tires. The athlete assumes a semi-sumo deadlift position with his hands hooked under the edge of the tire. A neutral grip with palms facing each other is preferred as it takes some strain off of the bicep tendon; this will depend on space under the tire and at times a supinated position will be taken. The athlete will then lift upward, similar to the deadlift, then drive into the tire extending the hips, knees, and ankles (triple extension) to propel the tire upward and forward. Their hands then rotate around from hip height to chest height to push the tire over (Figure 3).
The overhead press is another very common strongman event (43) and is typically performed with a metal log, giant dumbbell, or axle. Athletes are allowed to use any method of getting the object from ground to overhead and often use a modified power clean movement for the clean portion and a push press movement for the overhead press portion. Although athletes are allowed to perform jerks or full cleans, the size and instability of the objects tends to favor a more controlled approach either in the form of a push press or a strict press. For more in-depth description of the implements and lifting instructions, readers are referred to Waller et al. (34) (Figure 4).
Although these exercises have been used for many years in strongman competition, for them to be applied effectively within strength and conditioning programs, we need to have a deeper understanding of the underpinning physiological responses to these exercises. Long-term training studies investigating the physiological effects of strongman exercises would give exercise professionals greater insight into how strongman exercises may be appropriately included in strength and conditioning programs. As there are currently no such long-term training studies, we must look to relevant research that has examined the acute physiological responses to strongman training and compare that with what is currently known about traditional methods of resistance training.
ACUTE PHYSIOLOGICAL RESPONSES
The American College of Sports Medicine (ACSM) released a position stand in 2011 with the goal of providing scientific evidence-based recommendations to health and fitness professionals in the development of individualized exercise prescriptions for apparently healthy adults of all ages. In this position stand, the ACSM reports evidence-based guidelines for the intensity and duration (using percentage of maximum heart rate, V[Combining Dot Above]O2max and rating of perceived exertion scales) of exercise toward improvement of physical fitness and wellbeing.
Berning et al. (3) examined the metabolic demands of pushing and pulling a 1960-kg motor vehicle. Six male strength athletes were required to attend 3 testing sessions. Sessions 1 and 2 were randomly assigned and entailed either pushing or pulling the 1960-kg motor vehicle as fast as possible over a flat 400-m course while heart rate and oxygen consumption were continuously recorded. Vertical jump was recorded immediately pre and post, and blood lactate levels were recorded immediately before and 5 minutes after. Session 3 was a treadmill V[Combining Dot Above]O2max test. The push took 6.00 minutes on average to complete while the pull took 8.20 minutes on average. After the first 50 m of the push/pull, oxygen consumption averaged 44–49% of treadmill max while heart rates averaged 90–92% of HRmax. It was observed that oxygen consumption and heart rate peaked within the first 100 m of both the pushing/pulling and that from that point on oxygen consumption and heart rate averaged 65 and 96% of treadmill maximum (50.3 mL·kg−1·min−1, HRmax 194 beats per minute) values respectively. Blood lactate values averaged 15.06 mmol post-pulling/pushing sessions, representing 131% of the treadmill V[Combining Dot Above]O2max test. Peak vertical jump also decreased from pre to post on average by 17%.
Berning et al. (3) noted 3 key points; peak exertion was achieved quickly somewhere between 50 and 100 m, the car push/pull is an extremely exhausting event with near maximal heart rates being maintained over several minutes, and this event is highly anaerobic with post–car push/pull lactate scores 31% greater than observed following the maximal treadmill test. Acute fatigue was substantial with vertical jump scores significantly decreasing and all subjects experiencing dizziness and nausea. Because of the extreme anaerobic energy output and level of fatigue involved, Berning et al. (3) recommended that the car push/pull should be considered an advanced form of training and be carefully and sparingly incorporated into the overall training plan (Table 1).
However, the car push/pull performed in the study of Berning et al. (3) was for 400 m, a much longer distance than the 20–30 m the majority of strongman competitors use to train this event (42). The greater duration was likely a key contributing factor to the high lactate outputs and decreases in vertical jump performance seen immediately postexercise. Future research could also examine the physiological responses to the truck pull as performed with heavier loads and over much shorter distances so to allow coaches' and exercise professional's deeper insight into the physiological responses to strongman training.
The heart rates and oxygen consumption observed with the 400-m car push/pull falls into the “vigorous” training zone set by the ACSM, although after the first 50 m, oxygen consumption for the push/pull were 44 and 49% of V[Combining Dot Above]O2max respectively, levels that fall within the ACSM's moderate activity level range.
When comparing the results of the car push/pull with different modalities of resistance training, we note that the car push/pull seems to be a more metabolically demanding exercise with higher heart rates achieved in a shorter period (96% HRmax on average after 6–8 minutes of car push/pull) than the traditional forms of resistance training. Relevant resistance training studies reported mean heart rates of 69% of treadmill maximum (8) following circuit weight training performed for 17 minutes, and 82% of age-predicted maximum heart rate (4) following 30 minutes of intermittent free weight squatting, placing them in the moderate and vigorous training zones, respectively (7). The circuit training study also recorded an oxygen consumption of 50% of V[Combining Dot Above]O2max after 17 minutes, meaning it could be defined as a moderate activity level according to the ACSM's guidelines. The entire circuit weight training produced similar peak oxygen consumption rates to the first 50 m of car push/pull. Despite 50 m of car push/pull producing similar peak oxygen consumption levels and higher heart rates (90–92% of maximum after 50 m) as the circuit weight training, the duration for the 50 m car push/pull is likely to be under 1 minute (as the 400 m took 6–8 minutes) while the average duration for 3 circuits to be completed was 17 minutes. It should be noted that the circuit weight training involved brief rest periods of up to 30 seconds between sets and exercises. Equated for time, car push/pull seems to be more metabolically demanding than the circuit training used in the study. Although loading would affect the magnitude of the metabolic demand placed on the body, the car push/pull seems to produce metabolic responses deemed favorable for metabolic conditioning and circuit style training and in practice is often performed for 20–30 m on a sled or similar implement (42).
Keogh et al. (16) examined physiological and biomechanical aspects of the tire flip, another common strongman event. Five resistance trained subjects who were experienced in the tire flip performed 2 sets of 6 tire flips with a 232-kg tire and 3 minutes of rest between sets. Heart rate and blood lactate were recorded across 5 time points throughout the session: immediately pre-set 1, immediately post-set 1, immediately pre-set 2, immediately post-set 2, and 2.5 minutes post-set 2. High heart rates of 179 beats per minute (92% age-predicted max) and lactate levels of 10.4 mmol/L were found at the conclusion of the second set of tire flips. Keogh et al. (16) concluded from the results that the tire flip seems to provide a relatively high degree of physiological stress. In the future, similar research would need to be conducted with larger sample sizes and athletes of varying degrees of experience to determine how factors such as training experience and exercise prescription factors, such as relative loading, rest periods, numbers of sets, and repetitions (reps), would influence this acute response.
When using the ACSM guidelines to categorize the tire flip, it falls into the vigorous training zone. Comparing the heart rate responses of the tire flip to resistance training modalities of circuit weight training (8) and free weight squatting (4), it is observed that heart rate response to the tire flip was greater. The tire flip exercise is similar in nature in some ways to the power clean because there is little or no eccentric motion and a powerful triple extension is imperative to a successful lift. Lactate response to the power clean has been reported to be 7.4 mmol/L following 3 sets of 9 reps, with 70–75% of 3RM and 2 minutes rest between sets (6). Although the tire flip produced a higher lactate output with less sets and reps, it is difficult to compare because of the tire being a set load and not individualized as a relative percentage of maximum.
Recent research performed by West et al. (35) examined the acute metabolic, hormonal, biochemical, and neuromuscular responses to a backward sled drag training session. West et al. (35) had 11 strength trained males with an average back squat of 180 kg and 4 years of weight training experience perform 5 sets of 2 × 20-m reverse sled drags with 75% of their bodyweight on an indoor running surface. Participants were instructed to drag the sled 20 m as fast as possible, rest for 30 seconds, and then drag the sled back; this was counted as 1 set, and participants performed 5 sets with 120 seconds of rest between sets. Hormonal measures assessed included salivary testosterone and cortisol, with metabolic measures including blood lactate and creatine kinase, and neuromuscular responses were measured through countermovement jumps (CMJs). Participants performed a dynamic warm-up, followed by 3 CMJs on a force platform. Baseline measures through saliva and blood were then collected 15 minutes later. Following blood and saliva collection, participants began the sled drag workout. On completion of the sled workout, participants performed 3 CMJs before saliva and blood collection. Participants then rested before the CMJs and blood/saliva collection was repeated at 15 minutes, 1 hour, 3 hours, and 24 hours post–sled drag.
The authors (35) observed CMJ to significantly decrease after sled dragging and remain significantly below baseline until recovering at 3 and 24 hours post–sled drag. No changes in creatine kinase were seen at any time point after sled dragging. Blood lactate increased to 12.4 mmol/L immediately after sled drag training and remained elevated at 9.0 mmol/L 15 minutes after sled drag training. Blood lactate remained elevated at 1 hour post–sled drag with 3.8 mmol/L before returning to baseline levels of 1.7 mmol/L at 3 and 24 hours post–sled drag. Testosterone peaked 15 minutes post–sled drag before decreasing below baseline at the 3 hours time point, with a further peak seen at 24 hours post. Cortisol concentrations tended to increase at 15 minutes post–sled drag before declining at 1 hour post. Three hours post, cortisol declined below baseline, and at 24 hours post, cortisol returned to baseline levels.
The lack of any significant sled drag-induced increase in creatine kinase was interpreted by West et al. (35) to indicate no significant muscle damage incurred from the sled drag session. A possible mechanism for this lack of muscle damage was the lack of use of stretch shortening cycle (eccentric followed by concentric) in the contractions required to pull the sled because a reverse sled drag is primarily concentric muscle action. With CMJ height returning to baseline at 3 hours post, it was conjectured that full recovery of neuromuscular function had occurred within this time. This result is consistent with the lack of muscle damage, as assessed by creatine kinase. The increase in testosterone was attributed to the increase in lactate, with the metabolic component to the session being an important stimulus for testosterone secretion. This was confirmed with the correlation (r = 0.67) between the change scores of testosterone and lactate (35). The increase of testosterone at 24 hours was said to be a rebound effect to aid in recovery. Cortisol was shown to be related to the changes in lactate, with the rise in cortisol suggested to reflect the metabolic demand placed on the body. Overall, the increases in lactate, testosterone, and cortisol post–sled drag were said to be indicative of a positive training stressor.
A limitation of the study was the lack of a control group to show the changes in hormonal markers were because of the sled drag and not natural diurnal variation. Likewise, the measurement times lasted only up to 24 hours postexercise, which may have been inadequate as changes in creatine kinase may take longer than 24 hours to peak (20,23,31). Therefore, the lack of any significant change in creatine kinase within this timeframe and the resulting interpretation of no muscle damage may have reflected this limitation (13,14).
Eccentric muscle actions have been linked to muscle damage and an increase in creatine kinase levels (26). This is consistent with other research showing creatine kinase levels were much lower following concentric-only exercise compared with eccentric-only exercise (26). Similar lactate responses were observed between the sled drag exercise and a reciprocal superset workout involving a total of 12 supersets opposed to 5 sets of the sled drag. West et al. (35) reported that cortisol levels increased by 54% 15 minutes after sled drag training session, before returning to baseline levels at 60 minutes posttraining and decreasing by 52% at 3 hours post. Similar results to the sled drag session were reported by Schilling et al. (28) who reported a 57% increase in cortisol 5 minutes post a free weight squat session, consisting of 3 sets of 10 reps at 70% of 1RM with 1 minute rest between sets. Two other studies reported significant increases in cortisol levels (5,11) but only from their hypertrophy training groups. The hypertrophy protocol implemented by Crewther et al. (5) involved 10 sets of 10 reps at 75% of 1RM, with half the sets performed on the supine squat and half on the smith machine squat; participants were given 2 minutes rest between sets. The hypertrophy protocol reported by Häkkinen and Pakarinen (11) was performed for 10 sets of 10 reps at 70% of 1RM with 3 minutes rest between sets on the free weight squat. It is possible that strongman training shares many similarities with common hypertrophy protocols regarding the duration of sets as well, which could be the reason for similar increases in cortisol to those of the hypertrophy training methods.
Ghigiarelli et al. (9) examined the acute salivary testosterone responses of 2 novel strongman training protocols compared with a common hypertrophy resistance training protocol. Sixteen male participants, who acted as their own control, completed 3 different protocols designed to match total volume, rest period, and intensity between the protocols. The protocols were hypertrophic (H), a strongman (ST), and mixed involving both strongman exercises and traditional gym exercises (XST). All protocols were performed to muscular failure with a 2-minute rest between sets and a 3-minute rest between exercises. The H protocol consisted of the squat, leg press, bench press, and seated row performed for 3 sets of 10 reps to failure at 75% of 1RM. Unlike earlier studies, the ST protocol consisted of multiple exercises, including the tire flip, chain drag, farmers' walk, keg carry, and atlas stone lift. The XST session included the tire flip, back squat, chain drag, bench press, and stone lift in that order. Gym exercises were loaded at 75% of 1RM performed for 10 reps. Each protocol was performed with a week of rest in-between to account for the changes in diurnal variation. Salivary testosterone was recorded immediately before, immediately after, and 30 minutes after each protocol. The H protocol induced testosterone increases of 137% immediately after, the ST protocol a 70%, and the XST protocol a 54% increase immediately after; however, there were no significant differences between groups.
Ghigiarelli et al. (9) concluded that strongman training seems to be an effective tool for increasing endogenous testosterone response in a similar pattern to that of recognized hypertrophic protocols. This increase in testosterone has been speculated to facilitate the growth response and increase in muscle protein synthesis (18). Although this position has recently been challenged (36–38), Ghigiarelli et al. (9) suggested that there is a larger body of research supporting the former (12,19,27,29,32,33). A viable reason for the large increases in testosterone when compared with the other research (5,11,28,30) is that the total volume of work performed and muscle mass used was higher than the majority of other studies, with subjects performing 5 exercises for 3 sets to muscular failure. Research has shown a relationship between volume and testosterone response (10).
The following practical applications provided are given based on existing research. It is acknowledged that the majority of existing studies in the field of strongman training is on acute responses with a lone study on short-term training (40). For more in-depth practical applications, strongman training would need to be researched with the use of training studies, examining the chronic effects over a period of months to years. Despite the limitations of the research, we can provide recommendations based on the acute responses (Table 2).
Traditional gym training methods are well established for the hypertrophy training block (1,18,21,22); however, recently strongman training was compared with traditional resistance training using exercises matched for biomechanical similarity and equal loading. Between-group differences indicated small positive changes in muscle mass in the strongman group compared with the traditional group, indicating strongman training may be a viable modality of training for the hypertrophy block of training (40). Large time under tension has been shown to have favorable effects on increasing muscle hypertrophy (25). For increasing muscle hypertrophy, researchers recommend sets of 8–12 reps with loads of 70–85% of 1RM performed for 3–4 sets (1,18,21,22). Sets with these parameters generally last 25–40 seconds and are somewhat comparable with strongman events that generally range from 30 to 60 seconds with loads that require the athlete to work for similar durations. These durations of 30–60 seconds are commonly used by competitive strongman athletes when performing 20–50 m sets of farmers' carries and 30-m truck pulls (42). Strength and conditioning coaches often use sleds, farmers' walks, and tire flips in the training prescription for non-strongman athletes, making use of these implements to train metabolic conditioning, explosive strength/power, and muscle endurance (39). Because of the horizontal nature of the exercises, it is problematic to prescribe based on 1RM percentage because these exercises are often performed for a set horizontal distance and the resistance force may also be influenced by the friction force, especially for events like the truck or sled pull.
Strongman exercises also require multiple large muscle groups to contract simultaneously; exercises such as the farmers' carry or yoke walk require powerful co-contraction of multiple muscle groups, including core, upper-body, and lower-body musculature (24). Multiple large muscle groups contracting simultaneously have been shown to be a great stimulus for the metabolic and hormonal responses believed important for muscle hypertrophy (12).
Based on the above research, strength and conditioning coaches looking to prescribe strongman exercises with the intent of increasing muscular hypertrophy should implement exercises such as the sled drag and farmers' walk, with each set lasting 30–45 seconds for 3–4 sets with 90–120 seconds of rest, and loads that allow the athlete to complete at least 30 seconds of an exercise before muscular failure.
Research on strongman exercises also shows large metabolic and cardiovascular responses, indicating that it could be used for both metabolic and cardiovascular conditioning. Coaches looking to implement strongman exercises as a means of developing metabolic conditioning should look at prescribing exercises such as the tire flip, sled drag, and truck pull/sled drag for sets of a minimum of 30 seconds because this has been reported to produce lactate levels ranging from 10 to 16 mmol/L (17,35). Training adaptations to lactate levels of this magnitude may cause adaptations in lactate production, clearance mechanisms, and tolerance levels that may lead to an improvement in performance (15). Coaches looking to implement longer sets of strongman exercises may wish to split the duration between different exercises to cover a larger amount of musculature as the metabolic conditioning will be exclusive to active muscle groups.
Strongman exercises can also effectively be used as general conditioning exercises. Research has shown heart rate and oxygen consumption levels ranging from moderate to near maximal on the ACSM's intensity chart when performing strongman exercises. According to the ACSM, those looking to increase their general fitness should perform 30–60 minutes of moderate-intensity exercise per day or 20–60 minutes of vigorous activity. Based on the ACSM's guidelines, we recommend coaches implement strongman exercises, such as sled drags, tire flips, and car pushes, for sets of 1–2 minutes in a circuit format, with the total time equating to 20–30 minutes. An example of this could be 5 different exercises performed for 1 minute each for 5 rounds with 1-minute rest in between. Care would need to be taken to prescribe a load that the individual is capable of performing for the full minute. Coaches should also be aware that this form of training is likely to have a large metabolic component to it and that optimal recovery strategies should be in place.
Strength and conditioning coaches could also use strongman training as a means of training multiple qualities at a single time. This would help with training efficiency and allow coaches to spend more time on other qualities. An example of this may be in the sport-specific training phase where skill work is being performed in much higher volumes. In the sport-specific phase, a coach could use strongman training in a circuit format to maintain an athlete's anaerobic conditioning and strength in a single session, as opposed to having to train the 2 qualities separately. Sled pulls may be a particularly useful exercise in this in-season context because of their reduced creatine kinase levels and quicker anaerobic power recovery times (35), acknowledging that their muscular action and contraction types are not completely specific to all athletic activities. Furthermore, it has been speculated that strongman training may lead to greater adherence to resistance training programs because of the novelty and challenging nature of the exercises, often allowing athletes to train outdoors (44).
Strongman training also has its limitations. Winwood et al. (41) performed a retrospective survey of 213 strongman competitors looking at injury epidemiology. Winwood et al. (41) observed that strongman athletes were 1.9 times more likely to sustain an injury when performing strongman implement training compared with traditional training when matched to training exposure. Furthermore, as many strongman exercises require such high levels of core stability, much of the injury risk may be on the lower back (24). Because of these risks, significant coaching is required by strength and conditioning coaches looking to implement strongman training into their athletes' programs. It is imperative that they take the time to coach their athletes in proper technique and monitor them closely. It should also be noted that to date there has been no specific research on strongman training for females.
Another issue of strongman training is the greater challenge in precisely quantifying and altering training load for a number of individuals within the same session (2). Quantifying training load is most difficult for horizontal pulling and pushing exercises such as heavy sled pulls because of the coefficients of friction (static and dynamic) between the resistance and ground would need to be measured. Other exercises such as tire flips, keg carries, and stone lifting can present problems as the loads may be too heavy or too light to apply sufficient loading for some of the athletes. However, other exercises such as yoke walks, farmers' walks, and sled pulls can quite quickly have their loads changed by adding or removing plates.
Strength and conditioning coaches using tire flips, keg carries, and stone lifts should have access to a range of different sized implements. This will help to ensure that movement competency is adhered to with lighter loads on strongman implements before progressing to heavier implements like using a barbell squat or power clean.
1. Ahtiainen JP, Pakarinen A, Alen M, Kraemer WJ, Short K. Short vs long rest period between the sets in hypertrophic resistance training: Influence on muscle strength, size, and hormonal adaptations in trained men. J Strength Cond Res 19: 572–582, 2005.
2. Baker D. Strongman training for large groups of athletes. J Aust Strength Cond 16: 33–34, 2008.
3. Berning J, Adams K, Climstein M, Stamford B. Metabolic demands of “junkyard” training: Pushing and pulling a motor vehicle. J Strength Cond Res 21: 853–856, 2007.
4. Bloomer RJ. Energy cost of moderate-duration resistance and aerobic exercise. J Strength Cond Res 19: 878–882, 2005.
5. Crewther B, Cronin J, Keogh J, Cook C. The salivary testosterone and cortisol response to three loading schemes. J Strength Cond Res 22: 250–255, 2008.
6. Date AS, Simonson SR, Ransdell LB, Gao Y. Lactate response to different volume patterns of power clean. J Strength Cond Res 27: 604–610, 2013.
7. Garber CE, Blissmer B, Deschenes MR, Franklin BA, Lamonte MJ, Lee M, Nieman DC, Swain DP. Quantitiy and quality of exercise. Med Sci Sports Exerc 11: 1334–1359, 2011.
8. Garbutt G, Boocock MG, Reilly T, Troup JDG. Physiological and spinal responses to circuit weight-training. Ergonomics 37: 117–125, 1994.
9. Ghigiarelli JJ, Sell KM, Raddock JM, Taveras K. Effects of strongman training on salivary testosterone levels in a sample of trained men. J Strength Cond Res 27: 738–747, 2013.
10. Gothshalk LA, Loebel CC, Nindl B, Putukian BC, Sebastianelli WJ, Newton R, Häkkinen A, Kraemer W. Hormonal responses of multiset versus single-set heavy-resistance exercise protocols. Can J Appl Physiol 22: 244–255, 1997.
11. Häkkinen K, Pakarinen A. Acute hormonal responses to two different fatiguing heavy-resistance protocols in male athletes. J Appl Physiol (1985) 74: 882–887, 1993.
12. Hansen S, Kvorning T, Kjaer M, Sjogaard G. The effect of short-term strength training on human skeletal muscle: The importance of physiologically elevated hormone levels. Scand J Med Sci Sports 11: 347–354, 2001.
13. Howatson G, Hough P, Pattison J, Hill JA, Blagrove R, Glaister M, Thompson KG. Trekking poles reduce exercise-induced muscle injury during mountain walking. Med Sci Sports Exerc 43: 140–145, 2011.
14. Howatson G, McHugh MP, Hill JA, Brouner J, Jewell AP, VanSomeren KA, Shave RE, Howatson SA. Influence of tart cherry juice on indices of recovery following marathon running. Scand J Med Sci Sports 20: 843–852, 2010.
15. Juel C, Klarskov C, Nielsen JJ, Krustrup P, Mohr M, Bangsbo J. Effect of high-intensity intermittent training on lacate and H + release from human skeletal muscle. Am J Physiol Endocrinol Metab 286: E245–E251, 2004.
16. Keogh J, Payne A, Anderson B, Atkins P. A brief description of the biomechanics and physiology of a strongman event: The tire flip. J Strength Cond Res 24: 1223–1228, 2010.
17. Keogh JW, Newlands C, Blewett S, Payne A, Chun-er L. A kinematic analysis of a strongman-type event: The heavy sprint-style sled pull. J Strength Cond Res 24: 3088–3097, 2010.
18. Kraemer WJ, Ratamess NA. Hormonal responses and adaptations to resistance exercise and training. Sports Med 35: 339–361, 2005.
19. Kvorning T, Andersen M, Brixen K, Madsen K. Suppression of endogenous testosterone production attenuates the response to strength training: A randomized, placebo–controlled, and blinded intervention study. Am J Physiol Endrocrinol Med 291: E1325–E1332, 2006.
20. Lee J, Clarkson PM. Plasma creatine kinase activity and glutathione after eccentric exercise. Med Sci Sports Exerc 35: 930–936, 2003.
21. Linnamo V, Pakarinen A, Komi PV, Kraemer WJ, Häkkinen A. Acute hormonal responses to submaximal and maximal heavy resistance and explosive exercises in men and women. J Strength Cond Res 19: 566–571, 2005.
22. MaCaulley G, McBride J, Cormie P, Hudson M, Nuzzo J, Quindry J, Triplett T. Acute hormonal and neuromuscular responses to hypertrophy, strength, and power type resistance exercise. Eur J Appl Physiol 105: 695–704, 2009.
23. Manfredi TG, Fielding RA, O'Reilly KP, Meredith CN, Lee H, Evans WJ. Plasma creatine kinase activity and exercise-induced muscle damage in older men. Med Sci Sports Exerc 23: 1028–1034, 1991.
24. McGill S, McDermott A, Fenwick C. Comparison of different strongman events: Trunk muscle activation and lumbar spine motion, load, and stiffness. J Strength Cond Res 23: 1148–1161, 2009.
25. Mohamad NI, Nosaka K, Cronin J. Maximizing hypertrophy: Possible contribution of stretching in the interset rest period. Strength Cond J 33: 81–87, 2011.
26. Newham DJ, Jones A, Edwards RHT. Plasma creatine kinase changes after eccentric and concentric contractions. Muscle Nerve 9: 59–63, 1986.
27. Ratamess N, Kraemer W, Volek J, Maresh C, VanHeest J, Sharman M, Rubin MR, French D, Vescovi J, Silvestre R, Hatfield D, Fleck S, Deschenes M. Androgen receptor content following heavy resistance exercise in men. J Steroid Biochem Mol Biol 93: 35–42, 2005.
28. Schilling BK, Frya AC, Ferkin MH, Leonard ST. Hormonal responses to free-weight and machine exercise. Med Sci Sports Exerc 33: 1527, 2001.
29. Schoenfeld BJ. The mechanisms of muscle hypertrophy and their application to resistance training. J Strength Cond Res 24: 2857–2872, 2010.
30. Schwab R, Johnson GO, Housh TJ, Kinder JE, Weir JP. Acute effects of different intensities of weight lifting on serum testosterone. Med Sci Sports Exerc 25: 1381–1385, 1993.
31. Schwane JA, Buckley RT, Dipaolo DP, Atkinson MA, Shepherd JR. Plasma creatine kinase responses of 18- to 30-yr-old African-American men to eccentric exercise. Med Sci Sports Exerc 32: 370–378, 2000.
32. Spiering B, Kraemer W, Vingren J, Ratamess N, Anderson J, Armstrong L, Nindl B, Volek J, Häkkinen K, Maresh C. Elevated endogenous testosterone concentrations potentiate muscle androgen receptor responses to resistance exercise. J Steroid Biochem 114: 195–199, 2009.
33. Vingren J, Kraemer W, Ratamess N, Anderson JM, Volek J, Maresh C. Testosterone physiology in resistance exercise and training: The up-stream regulatory elements. Sports Med 40: 1037–1053, 2010.
34. Waller M, Piper T, Townsend R. Strongman events and strength and conditioning programs. Strength Cond J 25: 44–52, 2003.
35. West DJ, Cunningham DJ, Finn C, Scott P, Crewther BT, Cook CJ, Kilduff LP. The metabolic, hormonal, biochemical and neuromuscular function responses to a backward sled drag training session. J Strength Cond Res 28: 265–272, 2014.
36. West DW, Burd NA, Tang JE. Elevations in ostensibly anabolic hormones with resistance exercise enhance neither training-induced muscle hypertrophy nor strength of the elbow flexors. J Appl Physiol 108: 60–67, 2010.
37. West DW, Phillips SM. Anabolic processes in human skeletal muscle: Restoring the identities of growth hormone and testosterone. Phys Sportsmed 38: 97–104, 2010.
38. West DW, Phillips SM. Associations of exercise-induced hormone profiles and gains in strength and hypertrophy in a large cohort after weight training. Eur J Appl Physiol 112: 2693–2703, 2012.
39. Winwood PW, Cronin J, Dudson MK, Gill N, Keogh J. How coaches use strongman implements in strength and conditioning practice. Int J Sports Sci Coach 2013.
40. Winwood PW, Cronin JB, Posthumus L, Finlayson S, Gill ND, Keogh JW. Strongman versus traditional resistance training effects on muscular function and performance. J Strength Cond Res 2014. Published ahead of print.
41. Winwood PW, Hume PA, Keogh JW, Cronin JB. Retrospective injury epidemiology of strongman competitors. J Strength Cond Res 28: 28–42, 2014.
42. Winwood PW, Keogh J, Harris N. The strength and conditioning practices of strongman competitors. J Strength Cond Res 25: 3118–3128, 2011.
43. Winwood PW, Keogh J, Harris N. Interelationships between strength, anthropometrics, and strongman performance in novice strongman athletes. J Strength Cond Res 26: 513–522, 2012.
44. Zemke B, Wright G. The use of strongman type implements and training to increase sport performance in collegiate athletes. Strength Cond J 33: 1–7, 2011.