Recent eLetters

Letter to the Editors,

We read with interest the recent review by Bleakley and Davison (BJSM vol 44: 179-187)[1], which described the physiological and biochemical responses to cold water immersion (CWI) after exercise. The authors examined some of the acute cardiovascular responses that occur with CWI, such as changes in heart rate, blood pressure and cerebral blood flow. We noted, however, that they did not address the effects of CWI on heart rate variability (HRV), which provides an indication of cardiac autonomic nervous system (ANS) activity[2]. Exercise increases cardiac sympathetic activity and reduces cardiac parasympathetic activity[3]. But when multiple bouts of high-intensity exercise are performed without adequate recovery, the return of cardiac parasympathetic activity to resting levels is diminished[4, 5, 6]. There is evidence to suggest however, that CWI quickens the (post-exercise) return of cardiac ANS activity to pre-exercise levels, which may be indicative of an improved recovery state.

Water immersion on its own alters cardiac ANS activity. In thermoneutral water immersion, hydrostatic pressure is the primary factor that induces a mild compression of the peripheral vasculature[7], thereby increasing venous return[8] and baroreceptor loading[9], ultimately increasing cardiac parasympathetic activity. For example, cardiac and vasomotor sympathetic activity was suppressed [8], while cardiac parasympathetic activity was elevated [8,10] during thermoneutral water (30 - 34.5 degrees C) immersion and further elevated during cool water (26 - 27 deg C) immersion[9] compared with sitting out of the water. Collectively, these findings indicate that water immersion increases cardiac parasympathetic activity, and the effect is augmented with the addition of a cold stimulus[9, 12].

Extending the findings of Mourot et al.[9] at rest (i.e., without exercise), Al Haddad et al.[12] observed a greater increase in cardiac parasympathetic activity after immersion in cold (14 - 15 deg C) compared with warm (33 - 34 deg C) water following submaximal exercise. Thus, CWI (at ~14 deg C) provides a moderate cold stimulus that likely has an additive effect on the hydrostatic pressure, increasing peripheral vasoconstriction[7, 13], and also stimulating cold receptors in the skin, subcutaneous tissue and veins. Together, these responses likely augment cardiac parasympathetic stimulation[14].

In an applied setting with athletes, Buchheit et al.[4] and Parouty et al.[15] observed that 5 min of CWI during recovery between two supramaximal exercise bouts helped to restore cardiac parasympathetic activity. This response however, was not associated with improved 1-km cycling performance[4], and was detrimental to repeated 100-m sprint swimming times[15]. Currently, limited data exists on the relationship between parasympathetic activity and athletic performance; however, it appears that improved/faster post-exercise parasympathetic reactivation does not necessarily translate into better high-intensity exercise performance. Further study exclusively manipulating cardiac autonomic activity before exercise (e.g., through pharmacological means) might help clarify this question. Exercise performance in such short events (1 min) may be more closely related to the efficiency of the neuromuscular and anaerobic systems, with the cardiovascular and autonomic systems playing only minor roles. Furthermore, the increased parasympathetic background before a repeated high-intensity effort might compromise cardio-acceleration at exercise onset, limiting oxygen delivery and therefore performance[15]. Greater parasympathetic activity before exercise may be beneficial for longer events, when a blunted increase in heart rate together with the increased plasma volume as a consequence of fluid shift after immersion[16] can prevent excessive myocardial work and therefore maintain prolonged aerobic performance. Future work could address this concept.

To date, no study has examined the effect of CWI during consecutive days of exercise on cardiac ANS activity, however, CWI following exercise sessions, particularly high-intensity exercise, may help restore/maintain cardiac parasympathetic activity during consecutive days of training. A concurrent reduction in cardiac sympathetic and increase in parasympathetic activity may be related to perceptions of less stress[17, 18], and greater well-being or - - recovery [4, 15]. Together, these observations may also be associated with improved sleep quality (personal observations), thereby reducing the period required for full recovery. Finally, the recent findings by Lung et al.[11] also suggest that repeated CWI might accelerate acclimation to altitude by reducing sympathetic responses to hypoxic exposure, which could be of interest for sea-level athletes travelling to and competing at altitude. This cross-adaptive response highlights further potential benefits of CWI for athletes competing in various environments, and warrants future research.

In summary, in addition to the numerous physiological effects of CWI described by Bleakley and Davison (BJSM vol 44: 179-187)[1], the clear alterations of HRV and cardiac autonomic activity are also important to consider. The effects of CWI on cardiac parasympathetic activity and associated perceptions of recovery suggest that CWI may be most effective when used after the final session of the day, or at the end of the day, which could improve an athletes overall recovery process (i.e., perceived well-being and sleep quality). The effect of CWI on training program adaptation and recovery requires further investigation.

Authors and affiliations

Jamie Stanley1,2, Paul B. Laursen3,4, Jonathan M. Peake1,2, Martin Buchheit5

1The University of Queensland, School of Human Movement Studies, Brisbane, Australia

2Centre of Excellence for Applied Sport Science Research, Queensland Academy of Sport, Brisbane, Australia

3New Zealand Academy of Sport North Island, Auckland, New Zealand

4School of Sport and Recreation, Auckland University of Technology, Auckland, New Zealand

5Physiology Unit, Sport Science Department, Aspire, Academy for Sports Excellence, Doha, Qatar

Address for correspondence:

Jamie Stanley, School of Human Movement Studies, The University of Queensland, Brisbane, Queensland 4072, Australia; E-mail: j.stanley@uq.edu.au; Tel: +61 7 3365 6482; Fax: +61 7 3365 6877.

References

1. Bleakley CM, Davison GW. What is the biochemical and physiological rationale for using cold-water immersion in sports recovery? A systematic review. Br J Sports Med. 2010 March 2010;44:179-87.

2. Task-Force. Heart Rate Variability: Standards of Measurement, Physiological Interpretation, and Clinical Use. Circulation. 1996 March 1, 1996;93:1043-65.

3. Perini R, Orizio C, Baselli G, Cerutti S, Veicsteinas A. The influence of exercise intensity on the power spectrum of heart rate variability. Eur J Appl Physiol. 1990;61:143-8.

4. Buchheit M, Peiffer JJ, Abbiss CR, Laursen PB. Effect of cold water immersion on postexercise parasympathetic reactivation. Am J Physiol Heart Circ Physiol. 2009 February 1, 2009;296:H421-7.

5. Furlan R, Piazza S, Dell'Orto S, Gentile E, Cerutti S, Pagani M, et al. Early and late effects of exercise and athletic training on neural mechanisms controlling heart rate. Cardiovasc Res. 1993;27:482-8.

6. Hautala AJ, Tulppo MP, Makikallio TH, Laukkanen R, Nissila S, Huikuri HV. Changes in cardiac autonomic regulation after prolonged maximal exercise. Clin Physiol. 2001;21:238-45.

7. Wilcock IM, Cronin JB, Hing WA. Physiological response to water immersion: a method for sport recovery? Sports Med. 2006;36:747-65.

8. Miwa C, Sugiyama Y, Mano T, Iwase S, Matsukawa T. Sympatho-vagal responses in humans to thermoneutral head-out water immersion. Aviat Space Environ Med. 1997;68:1109-14.

9. Mourot L, Bouhaddi M, Gandelin E, Cappelle S, Dumoulin G, Wolf JP, et al. Cardiovascular autonomic control during short-term thermoneutral and cool head-out immersion. Aviat Space Environ Med. 2008;79:14-20.

10. Perini R, Milesi S, Biancardi L, Pendergast DR, Veicsteinas A. Heart rate variability in exercising humans: effect of water immersion. Eur J Appl Physiol. 1998;77:326-32.

11. Lunt HC, Barwood MJ, Corbett J, Tipton MJ. "Cross-adaptation" habituation to short repeated cold-water immersions affects the response to acute hypoxia in humans. J Physiol. Published Online First: 19 July 2010. 10.1113/jphysiol.2010.193458

12. Al Haddad H, Laursen P, Chollet D, Lemaitre F, Ahmaidi S, Buchheit M. Effect of cold or thermoneutral water immersion on post-exercise heart rate recovery and heart rate variability indicies. Auto Neurosci. Published Online First: 18 April 2010. doi:10.1016/j.autneu.2010.03.017

13. Vaile J, O'Hagan C, Stefanovic B, Walker M, Gill N, Askew CD. Effect of cold water immersion on repeated cycling performance and limb blood flow. Br J Sports Med. Published Online First: 16 March 2010. 10.1136/bjsm.2009.067272

14. Buchheit M, Laursen PB. Treatment of hyperthermia: is assessment of cooling efficiency enough? Exp Physiol. 2009;94:627-9.

15. Parouty J, Al Haddad H, Quod M, Lepretre PM, Ahmaidi S, Buchheit M. Effect of cold water immersion on 100-m sprint performance in well-trained swimmers. Eur J Appl Physiol. 2010;109:483-90.

16. Park KS, Choi JK, Park YS. Cardiovascular regulation during water immersion. Appl Human Sci. 1999;18:233-41.

17. Hjortskov N, Rissen D, Blangsted A, Fallentin N, Lundberg U, Sogaard K. The effect of mental stress on heart rate variability and blood pressure during computer work. Eur J Appl Physiol. 2004;92:84-9.

18. Jiang D, He M, Qiu Y, Zhu Y, Tong S. Long-range correlations in heart rate variability during computer-mouse work under time pressure. Physica A: Statistical Mechanics and its Applications. 2009;388:1527-34.

19. Hopkins WG, Marshall SW, Batterham AM, Hanin J. Progressive statistics for studies in sports medicine and exercise science. Med Sci Sports Exerc. 2009;41:3-13.

Conflict of Interest:

None declared

I recently read an article in the Wall Street Journal regarding football/soccer injuries amongst boys and girls. It referenced your medical study concerning the prevalence of knee injuries to the strong leg of boys, but to the weak leg of girls. As a former player of 20 years and coach for the past eight, I have a theory on this divergence. If a player strikes strongly through a ball, he lands on his striking leg (which is the strong leg for most youth players). The knee may turn when the player lands on this striking/strong leg. Also, if a defensive player is going hard to the ball, he is more likely to hit the leg that is planted, which would be the striking/strong leg in my scenario. While this is not always true, my guess is that fewer girls strike through the ball strongly. If this is not done, the player is more likely to maintain her plant/weak leg on the ground, rather than leaving that leg and landing on the striking/strong leg. Again, the plant leg is more likely to twist, and a defensive player is more likely to create contact with the leg that is planted on the ground. For this reason, many girls may be more likely to injure their weak/plant leg.

Conflict of Interest:

None declared

Dear Editor, We read with interest the article from Hasler et al. (2009) "Are there risk factors in alpine skiing? A controlled multicentre survey of 1278 skiers". In general, the answer is: 'yes, there are internal (e.g. gender, age, fitness, skill level, risk taking) and external (equipment, environment) risk factors' according to comprehensive model for injury causation by Bahr and Krosshaug (1). However, we would like to comment on the presented data and methods used because some results seem contrary to other studies in this research field. Firstly, Hasler et al. reported that skiers with new equipment have a higher risk of being injured. However, there seems a mistake in the presented data because in the abstract the Odds Ratio (OR) was 59 with a 95% confidence interval of 0.37-0.93 while in Table 1 the OR was 0.59. If the OR of 0.59 was correct, new equipment would decrease injury risk. In addition, what means new equipment? Did the authors compare carving skiers with traditional skiers as done by Burtscher et al. (2) showing a reduced injury rate since the introduction of carving ski? Where is the cut off between new and old equipment? In the discussion section, Hasler et al. stated that the results might be explained by a mismatch between the abilities of the skier and the equipment. Unfortunately, they did not include skill levels in their questionnaire. Several studies showed higher injury rates in less skilled skiers and snowboarders (3, 4) while more skilled skiers had a higher risk to sustain a more severe injury (5). Secondly, there seem mistakes concerning the presented data about snow conditions. In Figure 3, artificial snow versus old snow and fresh snow versus powder snow show OR <1 while in Table 1 the same OR are presented vice versa (OR 0.21 for old snow vs. artificial snow and OR 0.31 for old snow vs. fresh snow, respectively). It is the same with slush snow versus powder snow which is not a snow condition but a skiing condition in Figure 3 and powder snow vs. slush snow in Table 1, respectively. In addition, old snow seems to be in contrast to fresh snow. Does fresh snow mean powder snow? However, can old snow not be also old artificial snow? Therefore, it is not clear which snow condition actually increases or decreases injury risk. Thirdly, seasonal checking of skiing equipment showed a trend to decrease injury risk (OR: 0.46, p = 0.056). In our opinion, seasonal checking of skiing equipment includes primarily an adjustment of the bindings. In accordance, Burtscher et al. (2) showed that female carving skiers with a binding adjustment older than 1 year had a twofold knee injury rate compared to those with newly adjusted bindings. The release of a binding is primarily important in preventing injuries to the lower extremity. Therefore, it would be better to define risk factors with regard to the injured body location. Fourthly, injured skiers showed a higher readiness for risk taking in this study. In contrast, other studies reported that injured skiers did not take more risk but were less skilled compared to uninjured skiers (6-8). Therefore, it would make sense to include skill level. Fifthly, Hasler et al. showed a higher injury risk when skiing under bad weather conditions which is well in accordance with the study by Aschauer et al. (9). However, poor snow and weather conditions may be misjudged by injured skiers because they may look for an explanation as to why the injury occurred. In general, self-report to questions might lead to underreport or overreport of health-risk behaviours affected by cognitive and situational factors (10). Sixthly, gender has not been found to be a significant risk factor in this study. That might be due to the fact that Hasler et al. did not differentiate between injured parts of the body, e.g. females have a higher knee injury risk (2) and males have a higher head injury risk (11) compared to the other gender. Seventhly, Hasler et al. calculated that injury risk is higher when warming up. This result contrasts general preventive recommendations (12) and also the findings by Ruedl et al. (13) who demonstrated a twofold injury reduction in a cohort of 36.000 participants of 12 ski schools when warming up. Eighthly, there seems a mistake concerning the presented data about drug consumption. Figure 3 shows an OR > 1 for abstinence from drugs while in Table 1 drug consumption was presented vice versa. In addition, in Table 1 an OR of 5.92 was presented while in the discussion the OR was 1.78 for drug consumption. Since a case control design was used, the amount of exposure to the suggested risk factors was unknown which should be taken into account when interpreting the results (14). In the study by Hasler et al. the controls were interviewed when coming off slopes after skiing. This implies that controls skied probably more than 3 hours although other studies showed that most injuries to the lower extremity occurred within the first 2 or 3 hours of skiing (15, 16). A total of 782 patients were recruited over a period of 5 and a half month and 496 controls were interviewed in six different ski resorts. This means an average of about 83 controls per ski resort and an average of 15 uninjured skiers per month, respectively. However, Hasler et al. (2009) did not specify when controls have been recruited, e.g. every second day. A continuous recruitment of controls seems of utmost importance to compare prospectively potential external risk factors like snow, weather and slope conditions. In general, a prospective study design concerning internal and external risk factors in relation to gender and type of injury should be used. However, at least a case-control-design should be applied matching controls according to gender, age and skill level. References 1. Bahr R, Krosshaug T. Understanding injury mechanisms: a key component of preventing injuries in sport. Br J Sports Med 2005; 39: 324-329. 2. Burtscher M, Gatterer H, Flatz M et al. Effects of modern ski equipment on the overall injury rate and the pattern of injury location in Alpine skiing. Clin J Sport Med 2008; 18:355-357. 3. Langran M, Selvaraj S. Increased injury risk among first-day skiers, snowboarders, and skiboarders. Am J Sports Med 2004;32:96-103. 4. Hagel B. Skiing and snowboarding injuries. Caine DJ, Maffulli (eds.): Epidemiology of Pediatric Sports Injuries. Individual Sports. Med Sport Sci. Basel. Karger,2005;48:74-119. 5. Goulet C, Hagel BE, Hamel D, et al. Self-reported skill level and injury severity in skiers and snowboarders. J Sci Med Sport 2008; doi: 10.1016/j.jsams.10.002 6. Bouter LM, Knipschild PG, Feij JA, et al. Sensation seeking and injury risk in downhill skiing. Person. Individ. Diff. 1988;9:667-73. 7. Cherpitel CJ, Meyers AR, Perrine MW. Alcohol consumption, sensation seeking and ski injury: a case-control study. Journal of Studies on Alcohol 1998;59:216-21. 8. Goulet C, Regnier G, Valois P, et al. Injuries and risk taking in alpine skiing. ASTM STP 1397, Skiing Trauma and Safety: Thirteenth Volume, RJ Johnson, P Zucco, JE Shealy (eds.), ASTM International, West Conshohocken, PA, 2000:139-46. 9. Aschauer E, Ritter E, Resch H et al. Injuries and injury risk in skiing and snowboarding. Unfallchirug 2007; 110: 301-306. (in German) 10. Brenner ND, Billy JOG, Grady WR. Assessment of factors affecting the validity of self-reported health-risk behavior among adolescents: evidence from the scientific literature. J Adolesc Health 2003;33:436-457. 11. Mueller BA, Cummings P, Rivara FP, et al. Injuries of the head, face, and neck in relation to ski helmet use. Epidemiology 2008;19:270-76. 12. Koehle MS, Lloyd-Smith R, Taunton JE. Alpine ski injuries and their prevention. Sports Med 2002; 32 (12): 785-793. 13. Ruedl G, Sommersacher R, Woldrich T et al. A structured warm-up program to prevent injury in recreational skiers. Senner V, Fastenbauer V, Boehm H (eds.): Book of Abstracts of the 18th Congress of the International Society for Skiing Safety, Garmisch-Partenkirchen, Germany, April 26 to May 02 2009, 77. 14. Vandenbroucke JP, von Elm E, Altman DG et al. Strengthening the reporting of observational studies in epidemiology (STROBE): explanation and elaboration. Epidemiology 2007;18 (6): 805-835. 15. Ungerholm S, Engkvist O, Gierup J et al. Skiing injuries in children and adults: a comparative study from a 8-year period. Int J Sports Med 1983; 4 (4): 236-240. 16. Ruedl G, Schranz A, Fink C et al. Are ACL injuries related to perceived fatigue in female skiers? ASTM International 2010; 7 (4), Paper ID JAI102747

Conflict of Interest:

None declared

von Willebrand's disease is an inherited bleeding disorder which can affect the quantity /- the quality of von Willebrand factor. It is more common than haemophilia and there are 3 main types.

Type 1 (by far the most common and accounting for > 70% of cases) is usually associated with mild bleeding symptoms (epistaxis, easy bruising, menorrhagia etc) and may be diagnosed later in life.

Type 2 is the second commonest and has several different sub-types. It is associated with qualitative changes in von Willebrand factor (unlike Type 1 which is associated with deficiency but normal quality vWF).

The rarest but most severe type is Type 3 and this behaves similarly to severe haemophilia.

von Willebrand disease is different disease from haemophilia and not X-linked like haemophilia. It can occur in boys or girls and can be inherited in an autosomal recessive or dominant manner depending on the type.

Conflict of Interest:

None declared

Dear Editor,

My colleagues and I read with great interest your Editorial proposing a new paradigm of inactivity physiology. This would be useful. In order to properly discuss all aspects of any problem it clearly is necessary to be able to name each precisely.

There is a clear distinction between not exercising and prolonged sitting, though I would suggest that "seated immobility" as advocated by Beasley et al [1] describes the latter more precisely than "sedentary behaviour", and could include the concept of muscular physio- and pathophysiology.

Never before in the history of mankind have we been faced with such an abrupt change of behaviour on such a global scale as that following the advent of cars, TV, and notably the PC. Society, whilst very concerned about viruses and worms damaging their computers, is seemingly heedless of the health risks PCs pose their users.[2]

Long periods of seated immobility have become the norm, apparently bringing in their train a multitude of serious health problems, even death. A 20 year old Korean is reported of dying of a thromboembolism after 80 hrs of sitting at a computer display station.[2] Interestingly, during the London Blitz the introduction of bunk beds to air raid shelters reduced this form of death in elderly females who had previously had to sit for long hours.[3] But it will take considerable time for this anecdotal material to be proved at a scientific level so overwhelmingly as to compel changes in human behaviour.

I work in the field of rehabilitation of musculoskeletal disorders. Cardiovascular, metabolic, even mental health are all related to musculoskeletal health which, to be maintained, needs regular motion.

You alluded to the need for mechanistic studies. Some years ago computer operators began presenting with neck and shoulder pain. I hypothesized that this might be related to seated immobility. But it is difficult to demonstrate what is happening in a body held immobile for long periods.

Until recently the chief tool used to study tension in muscle has been electromyography (EMG), giving data on that part of muscle behaviour mediated by the neural system. But in order to fully characterise muscle in responding to gravitational forces on the human body we also need to take into account its spring-like behaviour in relation to lever-like bones, as well as its viscoelasticity. Such full characterisation needs to be based on direct measurement of the physical state of the muscle itself.

Simpson's report was intriguing. Could changing from sitting to lying make a significant difference in the tension in a muscle? The simple method to demonstrate any difference is by palpation of the relevant muscle, the upper trapezius (UT) in this case, which did affirm the supposition. But we needed to be able to report and replicate our findings, and for that new technology was required. With the Myoton device and myometry [4] we demonstrated up to 20% decrease of both tension (Hz) and stiffness (N/m) in the UT.[5-7] It would seem that the force of gravity makes greater demand of muscle tension to maintain the seated position.

High muscle tension is associated with a higher risk of developing neck pain.[8] Could declining to the horizontal be crucial to recover from excessive muscle tension associated with seated immobility as Simpson suggested? We found that quick relief was obtained by lying down supine with flexed knees for two minutes each working hour, alternately simulating rhythmical walking movements with simple rotations of the shoulder girdle.

If our results could be verified in a larger study there would be good grounds for encouraging this kind of motional activity. In the workplace only a mat and roster would allow 10 people per hour this simple, effective, and cheap quick respite from excessive sitting. Similar things could be encouraged at home.

Even before all the scientific evidence describing the harmful effects of excessive immobility is in, might this not be a useful first step in reversing current behaviour? We owe this to our children. They learn from example.

References:

1. Beasley R, Heuser P, Raymond N. SIT (seated immobility thromboembolism) syndrome: a 21st century lifestyle hazard. N Z Med J. 2005;118(1212):U1379. http://www.nzma.org.nz/journal/118-1212/1376/ 2. Lee H. A new case of fatal pulmonary thromboembolism associated with prolonged sitting at computer in Korea. Yonsei Med J 2004;45:349-351. 3. Simpson K. Shelter deaths from pulmonary embolism. Lancet 1940;2:744. 4. Vain A. A method and device for recording mechanical oscillations in soft biological tissues, United States Patent No. 6132385, 2000. 5. Viir R, Vain A, Virkus A, et al. Skeletal muscle tone characteristics in upright, supine and partial water immersion conditions. 57th International Astronautical Congress 2006;1:132-141. 6. Viir R, Virkus A, Laiho K, et al. Trapezius muscle tone and viscoelastic properties in sitting and supine positions. SJWEH Supplements 2007;3:76-80. 7. Viir R, Ranna L, Rajaleid K, et al. Lying back gives prompt tension decrease in upper trapezius muscle but not applied relaxation technique in fibromyalgia patients [abstract]. Scand J Rheumatol 2008;37 (suppl 123):P36. 8. Wahlstrom J, Hagberg M, Toomingas A, et al. Perceived muscular tension, job strain, physical exposure, and associations with neck pain among VDU users; a prospective cohort study. Occup Environ Med. 2004;61:523-8.

Conflict of Interest:

None declared