A brief resume of the history of cold-water immersion
Cold-water immersion (CWI) has been used for its therapeutic and physiological benefits for millennia, with historical references dating as far back as 3500 BC. The ancient Egyptians documented its use in the Edwin Smith Papyrus, highlighting the therapeutic effects of cold water, and cold therapy continued to gain traction over time. Notably, the ancient Greeks also utilised cold-water immersion for health purposes, social activities, and relaxation.
Hippocrates and the Medicinal Properties of Cold Water
Hippocrates, a prominent figure in the field of medicine during the 4th century BC, is well-known for his documentation on the medicinal properties of cold water. He recognized its analgesic effects and emphasized its healing properties. In his work On Airs, Waters, and Places, Hippocrates stated, “the water can cure everything,” underscoring the central role water played in medical treatment during that period (Tsoucalas et al., 2015). Additionally, cold water was widely used in ancient times to treat fevers, with Roman physician Claudius Galen advocating its use for patients suffering from tertian fever. Hundreds of years later, the British physiologist James Currie revisited this practice, using cold water to treat his own fevers and expanding the knowledge of cold therapy in the context of human physiology (Wang et al., 2006).
Currie played a pivotal role in advancing the understanding of the physiological effects of cold-water immersion. His research delved into the impacts of cold on several bodily parameters, including body temperature, pulse, and respiration. Notably, he provided some of the earliest records of human temperatures in both healthy and diseased states, as well as in experimental settings (Henderson, 1971). Currie's experiments, conducted in his “water cure establishment,” sought to prove the value of hydrotherapy. He is remembered for pushing the boundaries of understanding the physiological mechanisms involved in cold-water immersion, which laid the groundwork for future studies.
The Early 20th Century
Fast forward to the early 20th century, and cold-water immersion's role in human physiology continued to develop with the contributions of several scientists. One significant contributor was Edgar A. Hines Jr. (1906–1978), a physician who built upon previous work by Bayard T. Horton, which had described cold allergies in the late 1920s (Lamotte et al., 2021). Hines' most notable contribution was his development of the cold pressor test, which he used to study blood pressure variability. In his landmark 1932 paper, Hines demonstrated that immersing hands in cold water at 4–5 °C for 30 seconds produced significant changes in blood pressure responses in hypertensive individuals (Hines & Brown, 1932). His follow-up work examined vasomotor reactions to sympathectomy, helping to clarify the autonomic control involved in the cold pressor response (Hines & Brown, 1933). These studies contributed to a broader understanding of how the sympathetic and parasympathetic nervous systems respond to cold stimuli, highlighting the potential for autonomic conflict, which can lead to cardiac arrhythmias (Tipton et al., 2010).
By the Mid-20th Century
By the mid-20th century, the focus of cold-water immersion research shifted towards its potential benefits in post-exercise recovery. In the 1960s, D.H. Clarke was among the first to investigate CWI for post-exercise recovery (Clarke, 1963; Clarke & Stelmach, 1966). Although this line of research was promising, it took a backseat to studies that centered on survival during cold-water exposure. Much of the subsequent work focused on understanding cold shock responses and how different clothing types affected cold-water immersion. Professor Mike Tipton conducted extensive research during this time, contributing to the knowledge of cold shock responses, clothing effects, and adaptations to repeated cold-water immersion (Tipton & Golden, 1987; Tipton & Vincent, 1989; Golden & Tipton, 1988).
However, it wasn't until the late 1990s that the focus returned to investigating the role of cold-water immersion in recovery after physical exercise. Paddon-Jones and Quigley (1997) played a crucial role in shifting attention back to this area by employing exercise-induced muscle damage protocols to study how CWI affected functional, inflammatory, and psychophysical responses. Their work sparked a renewed interest in cold-water immersion as a tool for enhancing recovery, leading to a multitude of studies in the following decades. These studies adopted various exercise modalities, subject cohorts, and cooling durations, all with the aim of informing sports practices and improving recovery protocols.
Studies about Cold Water Benefits
As the number of studies increased, meta-analyses began to emerge, synthesizing the findings from individual research efforts to establish a more consistent understanding of CWI’s effects on recovery. Meta-analyses conducted by researchers like Leeder et al. (2012), Poppendieck et al. (2013), Hohenauer et al. (2015), and Machado et al. (2016) helped establish general guidelines for using cold-water immersion effectively. Based on these meta-analyses, current recommendations suggest a CWI protocol involving 10–15 minutes of immersion at water temperatures between 10 and 15 °C (Machado et al., 2016). Additionally, research has shown that an immersion dose of 1.1 (i.e., 11 minutes at 10°C) is necessary to significantly reduce muscle tissue temperature (Vromans et al., 2019). Studies have also demonstrated that immediate immersion post-exercise is more effective than delayed immersion (Brophy-Williams et al., 2011), and the depth of immersion appears to play a minimal role in recovery outcomes (Leeder et al., 2015).
Despite the progress made in understanding CWI’s benefits for recovery, the physiological mechanisms involved—particularly at the muscle level—remained largely overlooked for some time. Over the past decade, attention has shifted towards investigating how changes in muscle temperature and blood flow contribute to the recovery process. Studies have shown that post-immersion muscle temperature can decrease by up to 6.4 °C (Freitage et al., 2021), while limb and cutaneous blood flow may be reduced by 20–30% (Gregson et al., 2011). Advances in technology have enabled researchers to better assess the effects of cooling on muscle blood flow (Ihsan et al., 2013; Mawhinney et al., 2020; Choo et al., 2018), providing new insights into how CWI promotes recovery at the cellular level.
In addition to its benefits for post-exercise recovery, recent research has expanded to explore how cold-water immersion affects human skeletal muscle adaptation in response to endurance and strength training. Studies in cellular and molecular physiology have identified key regulatory pathways involved in these adaptations, shedding light on how cold-water exposure may influence muscle endurance (Joo et al., 2016; Ihsan et al., 2015) and strength (Roberts et al., 2015; Fyfe et al., 2019; Peake et al., 2020). This growing body of knowledge emphasizes the complexity of CWI’s effects on human physiology, demonstrating its potential to improve not only recovery but also long-term adaptations to training.
Conclusion
In conclusion, cold-water immersion has a long history of therapeutic use, stretching back thousands of years. While its application in treating fevers and enhancing recovery from exercise has evolved, contemporary research continues to uncover the intricate physiological mechanisms that underpin its benefits. From early studies by Hippocrates to modern investigations into muscle blood flow and molecular pathways, CWI remains a valuable tool in both clinical and sports settings. As research continues to develop, cold-water immersion may yet reveal further insights into optimizing human health, performance, and recovery,
