Hydrotherapy is a definition for exercise in warm water and is a popular treatment for patients with neurologic and musculoskeletal conditions. The goals of this therapy are muscle relaxation, improving joint motion and reducing pain. This therapy is been used for thousands of years.
Physiotherapists are often involved in hydrotherapy in a rehabilitation setting. Client satisfaction and adherence to this form of exercise is often high.The therapeutic effects are often enhanced by the social setting of the sessions.
Hygiene and infection control need be closely monitored.
- The warmth of water blocks nociception by acting on thermal receptors and mechanoreceptors, thus influencing spinal segmental mechanisms.
Warm water stimulates blood flow positively, which leads to muscle relaxation.
the hydrostatic effect may relieve pain by reducing peripheral edema and by dampening the sympatic nervous system activity.
Water exercises against resistance improves muscle strength. 
Difference between aquatic exercise and balneotherapy
Balneotherapy is hydrotherapy but without exercise and is also called “Spa therapy”. It is frequently used in alternative medicine as a disease cure and is very popular for treatment of all types of arthritis.
There are not much studies that describe the difference in therapy effects between aquatic exercise and balneotherapy without exercise. In the following review article, ‘Effectiveness of Aquatic Exercise and Balneotherapy’, results show that Aquatic exercise had a small significant effect on pain reduction, improvement of function, quality of life and mental health. Compared to balneotherapy, exercise in water is more effective for the treatment of musculoskeletal diseases than passive immersion. There are no long-term effects, so to keep the disease stable, it is necessary to frequently participate in water exercises.
It is not clear what exact the effect is of balneotherapy in musculoskeletal diseases because the studies involving this subject have poor methodological quality, which makes it difficult to determine the individual effect in this therapy.
see Aquatherapy for boxed table with absolute contraindications and serious contraindications.
Recent research - specific disorder subgroups
A systematic review in 2017 found that the effectiveness of hydrotherapy with Parkinson’s disease clients, with or without other therapies may improve balance and functional mobility with ABE [ aquatic based exercise]compared to LBE [land based exercise] A 2018 randomised trial found that the effectiveness of hydrotherapy on knee osteoarthritis clients had comparable results with ABE vs LBE . However client satisfaction and compliance was better in the hydrotherapy group. 
A 2014 study into the effectiveness of hydrotherapy on chronic low back pain people found that
"A two-month intensive aquatic therapy programme of high-frequency (five times/week) decreases levels of back pain and disability, increases quality of life, and improves body composition and health-related fitness in sedentary adults with chronic low back pain."
Hydrotherapy in patients with rheumatoid arthritis
The study of A. Billberg confirms that temperate pool exercise has a significant effect on endurance and flexibility of the muscles, in upper and lower extremities in patients with RA. To gain this endurance and flexibility, exercises against resistance (Eccentric and concentric exercises) are necessary. Recent studies also indicate that patients with low muscle function can improve their muscle endurance with low impact exercises. The vitality of patients with Rheumatoid arthritis who participate in exercises in water is significantly improved after the hydrotherapy session. 
Two trials compared hydrotherapy to land-based exercise and failed to find any long
term differences in quality of life, health status, pain or functional scores. When we compare aquatic exercises to no exercise at all, there is a significant improvement in reducing pain in patients who participated in aquatic exercises.
Hydrotherapy is an ancient form of therapy and is proving beneficial in treating many MSK and neurological conditions. Physiotherapists are well placed to be instructional in implementing many varied programs.
funny fact ......what direction does a chicken swim in.....cluckwise............hmmmmm
- Kamioka H, Tsutani K, Okuizumi H, Mutoh Y, Ohta M, Handa S, Okada S, Kitayuguchi J, Kamada M, Shiozawa N, Honda T. Effectiveness of aquatic exercise and balneotherapy: a summary of systematic reviews based on randomized controlled trials of water immersion therapies. Journal of Epidemiology. 2010 Jan 5:0910270113-.
- Eversden L, Maggs F, Nightingale P, Jobanputra P. A pragmatic randomised controlled trial of hydrotherapy and land exercises on overall well being and quality of life in rheumatoid arthritis. BMC musculoskeletal disorders. 2007 Dec;8(1):23.
- Kamioka H, Tsutani K, Okuizumi H, Mutoh Y, Ohta M, Handa S, Okada S, Kitayuguchi J, Kamada M, Shiozawa N, Honda T. Effectiveness of aquatic exercise and balneotherapy: a summary of systematic reviews based on randomized controlled trials of water immersion therapies. Journal of Epidemiology. 2010 Jan 5:0910270113-.Eversden L, Maggs F, Nightingale P, Jobanputra P. A pragmatic randomized controlled trial of hydrotherapy and land exercises on overall well being and quality of life in rheumatoid arthritis. BMC Musculoskeletal Disorders 2007;Vol.8:23
- Lee Health. Jumping into swim therapy. Available from:https://www.youtube.com/watch?v=E5EcUOT_3ZU [last accessed 15.2.2019]
- Pinto C, Salazar AP, Marchese RR, Stein C, Pagnussat AS. Is hydrotherapy effective to improve balance, functional mobility, motor status, and quality of life in subjects with Parkinson’s disease? A systematic review and meta-analysis. PM&R. 2018 Sep 25.
- Ofer Nitzan. Aquatic exercise routines for OA. Available fromhttps://www.youtube.com/watch?v=Q5eP0TpMiA8&t=191s [last accessed 15/2/2019]
- Dong R, Wu Y, Xu S, Zhang L, Ying J, Jin H, Wang P, Xiao L, Tong P. Is aquatic exercise more effective than land-based exercise for knee osteoarthritis?. Medicine. 2018 Dec;97(52).
- MEDICA EM. Efficacy of aquatic therapy for multiple sclerosis: a systematic review. European journal of physical and rehabilitation medicine. 2017 Feb 17.
- Bidonde J, Busch AJ, Webber SC, Schachter CL, Danyliw A, Overend TJ, Richards RS, Rader T. Aquatic exercise training for fibromyalgia. Cochrane Database of Systematic Reviews. 2014(10).
- Active Chiropractic. 8 low back exercises in the pool/hydrotherapy. Available fromhttps://www.youtube.com/watch?v=GjHMoj3HT8I&feature=youtu.be [last accessed 15/2/2019]
- Baena-Beato PÁ, Artero EG, Arroyo-Morales M, Robles-Fuentes A, Gatto-Cardia MC, Delgado-Fernández M. Aquatic therapy improves pain, disability, quality of life, body composition and fitness in sedentary adults with chronic low back pain. A controlled clinical trial. Clinical rehabilitation. 2014 Apr;28(4):350-60.
- A. Bilberg, M. Ahlme’n and K. Mannerkorpi. Moderately intensive exercise in a temperate pool for patients with rheumatoid arthritis: a randomized controlled study. Rheumatology 2005;44:502–508
- Gordon S. Doig. Evidence-based systematic review of the effectiveness of hydrotherapy in acute and chronic medical conditions. www.EvidenceBased.net.