CrossFit

Critical Analysis of CrossFit Training within the Health and

Fitness Domainsby

Sajeel Chaudhry

Presentation Overview

• CrossFit definition and principles• CrossFit training template• Evidence of CrossFit on improved physical

fitness• Supercompensation effect in CrossFit• Strength and Power development in CrossFit• Physical Fitness paradigm• Metabolic adaptations due to CrossFit• Summary

What is Crossfit?• Core strength and conditioning program with the aim to develop a broad, general and

inclusive fitness i.e. broad adaptation response (Glassman, 2010)• It aims to prepare individuals for any physical scenario which is unknown or

unknowable by using constantly varying, high intensity, functional movements (Glassman, 2010)

• It is aimed to cater for a wide population of activities including combat, survival, sports, general lifestyle and fitness (“Our speciality is not specialising” Glassman 2010)

• CrossFit focusses on maximising neuroendocrine response, power development, cross training with different modalities, high frequency of training with a prescription for nutrition

• At the heart of CrossFits philosophy is to improve the human body’s functionality, which it aims to achieve through a development hierachy on the CrossFit metholodolgy

Hierachy of Development in Crossfit Methodology

Sport

Weightlifting and Throwing

Gymnastics

Metabolic Conditioning

Nutrition

Principles of CrossFit!• Training comprises of constantly varied, high intensity, functional movements to

achieve aim of general, broad and inclusive fitness• CrossFit aims to increase work capacity across broad time and modal domains i.e.

increase power at all lengths of duration long or short, and varied activities• CrossFit is the “Sport of Fitness”. It keeps score, times workout and defines rules and

standards of performance• CrossFit adheres to 3 fitness standards:

Develop and optimise 10 general physical skills Cardiovascular/Respiratory endurance Stamina Strength Flexibility Power Speed Coordination Agility Balance Accuracy

Be able to perform any skill at any given time i.e. concept of a “hopper” Training should be able to develop the ability to perform well in all three metabolic pathways i.e.

phosphagen (ATP-PCr), glycolytic and aerobic systems

Template for CrossFit’s ProgramGymnastics (G)

• Air Squat• Pull-up• Push-up• Dip• Handstand Push-up• Rope Climb• Muscle-up• Press to Handstand• Back Extension• Sit-up• Jumps• Lunges

Metabolic Conditioning (M)

• Run• Bike• Row• Jump Rope

Weightlifting (W)

• Deadlifts• Cleans• Presses• Snatch• Clean and Jerk• Medicine Ball Drills• Kettlebell Swing

Evidence of CrossFit Training on Fitness Levels and PerformanceAuthor Study Tests Results

Smith et al. (2013) Improvements in aerobic capacity (VO2 max) and body composition

VO2 max Body composition

Improved VO2 and body

composition (P<0.05) Well trained subjects did not

reach statistical significance 16% of subjects injured in

program

Jeffrey (2012) CrossFit vs. ACSM Margaria Kalamen power Anaerobic step Cooper 1.5 mile run

CrossFit group outperformed ACSM

No statistical significance Above average subjects unable

to outperform ACSM

Gerhart (2013) CrossFit vs. Traditional Anaerobic Resistance Training

Body composition Flexibility Aerobic capacity Max strength Agility Max power Muscular endurance

Both groups showed improvements

CrossFit yielded better results however no statistical significance

Deadlift was statistically significant in CrossFit

Paine et al. (2010) Improvements in Army Physical Fitness Tests

Max reps push ups (2mins) Max reps of sit up (2mins) 2 mile run (as fast as)

Improvements in tests across all levels of previous training

Below average showed highest gains

However higher volume of training provided than previously

• CrossFit improves fitness when subjected to different test protocols• No significant difference in fitness improvements compared to other training programs• Plateau effect seen in relatively trained subjects• (Refer to Appendix A for detailed information)

Supercompensation in Frequent HIT Programs

• Supercompensation is the balanced relationship between the training performed and the regeneration phase which leads to improved physiological adaptation (Verkhoshanky & Siff, 2009)

• Supercompensation is based on the General Adaptive Syndrome (GAS), when loading applied incorrectly can cause a decline in performance and expose subjects to health and injury risks due to fatigue and stressors(Bompa & Haff, 2009)

• A subjects homeostasis state drops along with functional capacity post an exercise session due to fatigue, which must be dissipated within the correct time spans to achieve supercompensation (Supercompensation Cycle of a training session)

Supercompensation in Frequent HIT Programs

• If subjected to another high intensity training within 24-72 hours, overtraining may occur causing a decline in performance.

• When frequent high intensity sessions are provided the body is not able to respond appropriately and regeneration does not occur (Fry et al., 1994; Peterson et al., 2005)

• With additional high intensity sessions the time to the body’s homeostasis is prolonged

• Musculoskeletal injuries on the rise including Exertional Rhabdomyolysis (ER) due to ECP (Extreme Conditioning Programs) as popularity increases (Bergeron et al., 2011; Hadeed et al., 2011)

• Significant higher RPE, harder days per week and DOMS in Crossfit than ACSM guided programs (Bellovary, 2014)

Lack of Strength & Power Development in the CrossFit Training Template

• Muscular strength is a major contributor to many physical attributes including power and endurance (Stone et al., 2003; Paavolainen, 1999)

• Since Power = F x V, increasing force yields more power output. Thus strength is important in developing high power and also in the neuromuscular adaptations required for muscular power (Plisk & Stone, 2003)

• Maximal strength and power are the fundamental pillars upon which other physical capabilities such as muscular endurance and task specific performances can be expanded (Kraemer & Szivak, 2012)

• Though for the untrained subject CrossFit does provide strength gains, randomness in the CrossFit training program cannot fundamentally provide strength gains to appropriately provide a foundation for high explosive power such as olympic lifts

• Preferred method of strength training combines free weights with large muscle mass exercises (Bompa & Haff, 2009)

• Cycle of at least 2 weeks before a Strength and Power training session is repeated. Detraining of a bio-motor ability is seen as little as 2 weeks (Garcia-Pallares et al., 2010)

• Since bulk of the training comprises of HIIT, metabolic adaptations are comparable to traditional endurance training (Burgomaster et al., 2008). Coupled with metabolic conditioning likelihood of interference effect to increase (Wilson et al., 2012)

Physical Fitness Paradigm• Fitness is defined as the ability to cope with the demands of a specific task efficiently and safely

(Verkhoshanky & Siff, 2009)• Main biomotor abilities are Strength, Speed & Stamina though flexibility & skill are also factors

related to fitness (Verkhoshanky & Siff, 2009; Bompa & Haff, 2009)• However fitness is not simply measured by the above components but also by the specificity of

fitness required by the activity (Verkhoshanky & Siff, 2009)

• Due to the specificity of the fitness required there will always be a dominant biomotor ability• CrossFit claims to improve the 10 physical skills and also targets enhancing specialised

professions such as combat, survival and sports without understanding the dominant biomotor ability of a given activity

• Conjugated training has shown to improve different biomotor abilities in a periodised fashion (Plisk & Stone, 2003). However the random nature of the CrossFit methodology does not allow to develop these biomotor abilities

Performance Enhancement due to the 3 Metabolic Pathways

• CrossFit states “Training should be able to develop the ability to perform well in all three metabolic pathways i.e. phosphagen (ATP-PCr), glycolytic and aerobic systems”

• Contribution from the 3 energy pathways (phosphagens, glycolysis & aerobic) are active at all times however relative contribution to ATP re-synthesis changes depending on intensity, recovery periods, duration and frequency of bouts performed (Maclaren & Morten, 2012; Gibala, 2007)

• Peak and mean power outputs decrease during HIIT (High Intensity Intermittent Exercise) if recovery periods are not sufficient for PCr re-synthesis (Gaintanos et al., 1993)

• For almost complete re-synthesis of PCr 4mins of complete recovery are sufficient in order to maintain peak and mean power outputs during maximal effort (Parolin et al., 1999; Bogdanis et al., 1996)

Performance Enhancement due to the 3 Metabolic Pathways

Energy Source Enzyme Activity Bout Duration Bout Recovery Training Programme

Phosphagens Myokinase (MK)-ADP to ATP

6-30 sec 45-60 sec 4-6 weeks, 4 times per week

Phosphagens Creatine Phosphokinase (CPK)- PCr regeneration for ATP fuelling

6 secs 2-3 mins 4-6 weeks, 4 times per week

Anaerobic Glycolysis Phosphofructokinase,Hexokinase, Phosphorylase, Pyruvate Dehydrogenase, Lactate Dehydrogenase

15-30 secs 30-45 secs 2-6 weeks, 3 times per week

Oxidative phosphorylation

Succinate Dehydrogenase (SDH) and Citrate Synthase (CS)

>15 secs 45sec-2mins 4 weeks, 3 times per week

Power

Endurance

• Randomness in program (WOD & As many rounds as possible) does not target enzyme activity for power development.

• Bulk of training occurring at anaerobic and oxidative glycolyis• (Refer to Appendix B for detailed information)

Summary• CrossFit provides improvements in many fitness tests domains, however this is only

seen in relatively untrained individuals who will adapt and show improvement to any stimuli that is provided

• High frequency of high intensity sessions has the risk of overtraining, and hence leads to increased injuries. Military and combat sectors are now re-assessing the efficacy of ECP’s such as CrossFit due to the high incidents of injuries

• Lack of strength development which is the fundamental biomotor factor and a pre requisite for power development

• Lack of training plan which targets improving multiple biomotor abilities• Metabolically, power development enzyme activity is not targeted and predominantly

aerobic glycolysis becomes the main energy source• Needs analysis needs to be performed on the group of subjects being trained before

HIIT such as CrossFit provided• SAID (Specific Adaptation to Imposed Demands)- Body adapts with a specific type of

fitness to any demands which may be regularly imposed on it, provided the loading does not exceed the adaptive capabilities of the body at the time

• Use Periodized plan and individualisation• Due to the lack of strength and power development variations of CrossFit have

already developed e.g. CrossFit bias

Questions?

ReferencesAdams, G.M., & Beam, W.C. (2008). In: Barrosse, E., Johnson, C., Rothenberger, M. et al., (Eds). Exercise physiology: Laboratory

manual (5th Edition). New York, NY: McGraw Hill.

Bellovary, B.N. (2014). The perceived demands of crossfit. (Masters Thesis) Northern Michigan University, United States

Bergeron MF, Nindl BC, Deuster PA, Baumgartner N, Kane SF, Kraemer WJ, et al. (2011) Consortium for health and military performance and american college of sports medicine consensus paper on extreme conditioning programs in military personnel. Current Sports Medicine Reports ,10: 383 –389.

Blair, S.N., Kohl, H.W., Paffenbarger, R.S., Clark, D.G., Cooper, K.H., & Gibbons, L.W. (1989). Physical Fitness and call cause mortality, a prospective study of healthy men and women. Journal of American Medicine Association, 262: 2395-2401.

Bogdanis, G.C., Nevill, M.E., Boobis, L.H., & Lakomy, H.K. (1996). Contribution of phosphocreatine and aerobic metabolism to energy supply during repeated sprint exercise. Journal of Applied Physiology, 80, 876-884.

Bompa, T.O., & Haff, G.G. (2009). Periodization: theory and methodology of training. 5th eds, Human Kinetic.

Burgomaster, K.A., Hughes, S.C., Heigenhauser, G.J., Bradwell, S.N., & Gibala, M.J. (2005). Six sessions of sprint interval training increases muscle oxidative potential and cycle endurance capacity in humans. Journal of Applied Physiology, 98: 1985-1990.

.

ReferencesBurgomaster, K.A., Howarth, K.R., Phillips, S.M., Rakobowchuk, M., MacDonald, M.J., McGee, S.L. & Gibala, M.J. (2008).

Similar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans. Journal of Physiology. 586, 151-160.

Dawson, B., Fitzsimons, M., Green, S., Goodman, C., Carey, M., & Cole, K. (1998). Changes in performance, muscle metabolites, enzymes and fibre types after short sprint training. European Journal of Applied Physiology and Occupational Physiology, 78(1): 163–169.

Fry, A.C., Kraemer, W.J., Van Borselen, F., Lynch, J.M., Marsit, J.L., Roy, E.P., Triplett, N.T., & Knuttgen, H.G. (1994). Performance decrements during high intensity resistance exercise overtraining. Journal of Applied Physiology, 101:1664-1672.

Gaitanos, G.C., Williams, C., Boobis, L.H., & Brooks, S. (1993). Human muscle metabolism during intermittent maximal exercise. Journal of Applied Physiology, 75, 712-719

Garcia-Pallares, J., Sanchez-Medina, L., Perez, C.E., Izquierdo-Gabarren, M. & Izquierdo, M. (2010) Physiological effects of tapering and detraining in world-class kayakers. Medicine and Science in Sports and Exercise, 42(6): 1209-1214.

Gerhart, H.D. (2013). A comparison of crossfit training to traditional anaerobic resistance training in terms of selected fitness domains representative of overall athletic performance (Masters Thesis), Indiana University, Pennsylvania, United States.

Gibala, M.J. (2007). High intensity interval training: new insights. Sports Science Exchange, 20(2).

ReferencesGlassman, G. (2010). CrossFit training guide. CrossFit Journal, 111-115

Hadeed, M.J., Kuehl, K.S., Elliot, D.L., Sleigh, A. (2011). Exertional rhabdomyolysis after CrossFit exercise program. Medicine and Science in Sports and Exercise. 43(5): 224-225

Jeffery, C. (2012). CrossFit effectiveness on fitness levels and demonstration of successful program objectives. Arkansan University

Kraemer, W.J., & Szivak, T.K. (2012). Strength training for the warfighter. Journal of Strength and Conditioning Research. 26(7):S107-S118.

Linosier, M.T., Dormois, D., Perier, C., Frey, J., Geyssant, A., & Denis, C. (1997). Enzyme adaptations of human skeletal muscle during bicycle short-sprint training and detraining. Acta Physiologica Scandinavica, 161(4): 439-445.

MacDougall, J.D., Hicks, A.L., MacDonald, J.R., McKelvie, R.S., Green, H.J., & Smith, K.M. (1998). Muscle performance and enzymatic adaptations to sprint interval training. Journal of Applied Physiology, 84(1): 2138-2142.

MacLaren, D., & Morton, J. (2012). Biochemistry for sport and exercise metabolism. Chichester, West Sussex: Wiley-Blackwell

Mohr, M., Krustrup, P , Nielsen, J.J., Nybo, L, Rasmussen, M.K., Juel,C., & Bangsbo, J. (2007). Effect of two different intense training regimens on skeletal muscle ion transport proteins and fatigue development. American Journal of Physiology - Regulatory, Integrative and Comparative Physiology, 292(1): 1594-1602.

ReferencesPaine, J., Uptgraft, J., & Wylie, R. (2010). Crossfit study. In G. Glassman, Crossfit Journal, 1-60.

Parra, J., Cadefau, J. A., Rodas, G., Amigo, N., & Cusso, R. (2000). The distribution of rest periods affects performance and adaptations of energy metabolism induced by high-intensity training in human muscle. Acta Physiologica Scandinavica, 169, 157–166

Parolin, M.L., Chesley, A., Matsos, M.P., Spriet, L.L., Jones, N.L., & Heigenhauser, G.J.F. (1999). Regulation of skeletal muscle glycogen phosphorylase and PDH during maximal intermittent exercise. American Journal of Physiology, 277, E890-E900

Paavolainen, L., Hakkinen, K, Hamalainen, I., Nummela, A., & Rusko, H. (1999). Explosive strength training improves 5-km running time by improving running economy and muscle power. Journal of Applied Physiology. 86: 1527-1533.

Peterson, M.D., Rhea, M.R., & Alvar, B.A. (2005). Applications of the dose response for muscular strength development: a review of meta-analytic efficacy and reliability for designing training prescription. Journal of Strength and Conditioning Research, 19: 950-958.

Plisk, S.S., & Stone, M.H. (2003). Periodization strategies. Strength and Conditioning, 25: 19-37.

Roberts, A.D., Billeter, R., & Howald, H. (1982). Anaerobic muscle enzyme changes after interval training. International Journal of Sports Medicine, 3(1): 18-21

ReferencesRodas, G., Ventura, J.L., Cadefau, JA, Cusso, R., & Parra, J. (2000). A short training programme for the rapid movement of both

aerobic and anaerobic metabolism. European Journal of Applied Physiology, 82(1): 480-486.

Smith, M.M., Sommer, A.J., Starkoff, B.E., & Devor, S.T. (2013). CrossFit based high intensity power training improves maximal aerobic fitness and body composition. Journal of Strength and Conditioning, Vol 27, Num 11.

Stone, M.H., Sanborn, K., O’Bryant, H.S., Hartman, M., Stone, M.E., Proulx, C., Ward, B., & Hruby, J. (2003). Maximum strength-power performance relationships in collegiate throwers. Journal of Strength and Conditioning Research. 17: 140-147.

Thorstensson, A., Sjödin, B., & Karlsson, J. (1975). Enzyme activities and muscle strength after sprint training in man. Acta Physiologica Scandinavica, 94(1): 313–318.

Tremblay, A., Simoneau, J.A., & Bouchard, C. (1994). Impact of exercise intensity on body fatness and skeletal muscle metabolism. Metabolism Experimental and Clinical, 43: 814-818.

Verkhoshansky, Y., & Siff, M. (2009). Supertraining (6th Edition - Expanded Version ed.). Rome: Verkoshansky.

Wilson, J.M., Marin, P.J., Rhea, M.R., Wilson, S.M., Loenneke, J.P., & Anderson, J.C. (2012). Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises. Journal of Strength and Conditioning Research. 26(8):2293-2307.

APPENDIX A:Evidence of CrossFit Training on Fitness Levels and Performance

• Improvements in aerobic capacity (VO2) max and body composition (Smith et al., 2013) 10 week program of 43 subjects (23 males, 23 females) 5 days on 2 days off structure Weightlifting bias in training i.e. lack of randomness especially during single skill/effort days Statistically significant (P<0.05)increase in VO2 max (from 40 to 45 ml.kg-1 .min-1 ) and decrease in body fat (from 25 to 20%) in population

However for subjects that were well above average in aerobic fitness before the training program, did not achieve statistical significance in improving their V0 2 max [Fitness standards measured against table from Blair et al., (1989)]

16% of subjects dropped out due to overuse of injury (possibly trained subjects in CrossFit) Similar results in improved aerobic fitness and body composition recorded in HIIT training interventions (Burgomaster et al., 2005; Tremblay et al., 1994)

• CrossFit vs. ACSM recommendations for physical fitness (Jeffrey, 2012) 37 participants (30 males, 7 females) Participant selection (CrossFit training for 4 months 3-4 times/week, ACSM recommended physical fitness for 4 months) ACSM recommendations- 3-5days/week 30min cardio, 2-3/week strength & 2-3days/week stretching training Both groups tested on Margaria Kalamen Power, Anaerobic Step, Cooper 1.5 mile run CrossFit group achieved greater power, anaerobic and aerobic results however failed to reach a statistical significance Participants who were classified as above average in the anaerobic step up and 1.5 mile cooper run test in the CrossFit group were unable to outpeform the

ACSM guided physical fitness group of the same level [Fitness standards measured against table from Adams et al., 2008)

• CrossFit vs. Traditional Anaerobic Resistance Training (Gerhart, 2013) Domains of athletic performance tested – body composition, flexibility, aerobic capacity, maximum strength, agility, maximum power and muscular endurance

(NCSA) Traditional Anaerobic Training (TAR) – 4-5days/week, 60min anaerobic training (Structured moderate vigorous intensity by varying modality, intensity, tempo,

volume, frequency and rest) 38 male participants trained for at least 3 months previously (19 CrossFit, 19 TAR) Both groups tested on body composition, sit-and reach, 3-minute step test, 1-repetition maximum deadlift, pro agility test, standing broad jump, and the pushup

test Body composition, flexibility, aerobic capacity, maximum power yielded better test results in CF without any statistical significance. Maximum strength test

(deadlift) however was significantly higher in CF Agility and endurance was in favour of TAR without any statistical significance

APPENDIX A:Evidence of CrossFit Training on Fitness Levels and Performance

• Improvements in APFT (Army Physical Fitness Test) and 3 CrossFit benchmark workouts [1 rep max, for time & 3 rounds for repetitions] (Paine et al., 2010)

6 week training program 14 subjects (5 males, 9 females) 4 subjects had below average APFT scores with no CrossFit training 4 subjects had average APFT scores with little CrossFit training 6 subjects had above average APFT scores with CrossFit training Results showed a big range of improved work capacity (3.71%-41.92%, Average of 20.33%) Below average subjects showed highest gains The training program provided more volume of training than the subjects previously participated in

APPENDIX B:Performance Enhancement due to the 3 Metabolic Pathways

• CrossFit states “Training should be able to develop the ability to perform well in all three metabolic pathways i.e. phosphagen (ATP-PCr), glycolytic and aerobic systems”

• Contribution from the 3 energy pathways (phosphagens, glycolysis & aerobic) are active at all times however relative contribution to ATP re-synthesis changes depending on intensity, recovery periods, duration and frequency of bouts performed (Maclaren & Morten, 2012; Gibala, 2007)

• Peak and mean power outputs decrease during HIIT (High Intensity Intermittent Exercise) if recovery periods are not sufficient for PCr re-synthesis (Gaintanos et al., 1993)

• For almost complete re-synthesis of PCr 4mins of complete recovery are sufficient in order to maintain peak and mean power outputs during maximal effort (Parolin et al., 1999; Bogdanis et al., 1996)

• During HIE ATP splits to ADP and Pi which activates the enzyme Myokinase (MK) converting 2 molecules of ADP to ATP. MK activity has increased by 20% for 6-30sec maximal efforts with 45-60 sec recovery periods over a 4-6 week training program 4 sessions a week (Parra et al., 2000; Dawson et al., 1998; Thorstensson et al., 1975)

• Despite MK reaction ADP concentration increases hence contribution from PCr is 50% to re-synthesise ATP. This is achieved by the enzyme Creatine PhosphoKinase (CPK). CPK activity increases with short maximal bouts of 6 secs with rest periods from 2-3 minutes whereas longer duration bouts do not (Mohr et al., 2007; Roberts et al., 1982)

• Enzymes during anaerobic glycolysis (Phosphofructokinase, Hexokinase, Phosphorylase, Pyruvate Dehydrogenase, Lactate Dehydrogenase) become more active during longer duration efforts of greater than 15 secs with 2-6 week training programs (Rodas et al., 2000; MacDougall et al., 1998)

• Contribution from oxidative phosphorylation increases as the duration of effort increases and number of bouts increase by upto 80% despite 4min rest periods (Parolin et al., 1999). During oxidative phosphorylation enzymes activity such as Succinate Dehydrogenase (SDH) and Citrate Synthase (CS) have known to increase but only significantly for efforts longer than 15 secs (Linoisser et al., 1993; Dawson et al., 1998)