Short answer, "No."
If we apply what we know about specific adaptation to imposed demands, it is doubtful that the lower extremities will be challenged enough in the aquatic environment. The buoyancy of the water reduces weightbearing through the joints. Specialized pools with jets and aquatic equipment that attaches to extremities to increase resistance will provide a bit more challenge if the goal is to increase strength.
To increase strength, it is important to know the patient's one repetition maximum. After knowing that, you can then calculate the appropriate intensity the patient needs to be challenged to increase strength.
The aquatic environment can be an excellent choice for exercise. It just may not be the best environment for increasing lower extremity strength.
Below you will find a quick view of the abstract.
To investigate the effectiveness of aquatic exercise in improving lower limb strength in people with musculoskeletal conditions.
A systematic search used 5 databases, including MEDLINE, CINAHL, Embase, SPORTDiscus, and The Cochrane Library.
Randomized controlled trials evaluating aquatic exercise with a resistance training component for adults with musculoskeletal conditions compared with no intervention or land-based exercise were identified. Fifteen studies from the initial yield of 1214 met these criteria.
Data related to participant demographics, study design, and methods, interventions, and outcomes, including numerical means and SDs, were extracted independently by 2 reviewers.
Nine of the 15 studies were of high quality, scoring at least 6 on the Physiotherapy Evidence Database Scale. Limited consideration of the prescription of resistance in the aquatic exercise and application of resistance training principles existed. Low- or very low-quality evidence indicates there was no difference in average effect between aquatic exercise and no exercise in improving hip abductor strength (standardized mean difference [SMD], .28; 95% confidence interval [CI], -.04 to .59), knee extensor strength (SMD, .18; 95% CI, -.03 to .40), knee flexor strength (SMD, .13; 95% CI, -.20 to .45), or lower limb endurance (SMD, .35; 95% CI, -.06 to .77). Low-quality evidence indicates no difference in average effect between aquatic and land exercise for knee extensor (SMD, -.24; 95% CI, -.49 to .02) or flexor strength (SMD, -.15; 95% CI, -.53 to .22).
It is likely that the inadequate application of resistance in water is a significant contributor to the limited effectiveness of aquatic exercise interventions in improving hip and knee muscle strength in people with musculoskeletal conditions. Future research is needed to quantify resistance with aquatic exercises and to determine if using opportunities for greater resistance in aquatic rehabilitation and appropriate resistance training principles can be more effective in improving muscle strength.
Arch Phys Med Rehabil. 2017 Jan;98(1):173-186. doi: 10.1016/j.apmr.2016.08.472. Epub 2016 Sep 22.