Strength in Water®

Strength in Water®

Research-led aquatic strength training, explained by the inventor of AquaBLAST.

Most people who train in a pool work from instinct. They know water feels different and is easier on the joints, but not why, or how to turn pool time into real strength training. Strength in Water® is my effort to close that gap. Each issue takes one credible study, explains it in plain language, and gives you something to try in the pool. The research leads; AquaBLAST is one way to apply it. I'll always tell you when a study didn't test our product, because none of these did.

— Rob Magrino, inventor of AquaBLAST®

Get each new Strength in Water® issue by email. One research-backed issue every two weeks, plus pool workouts you can try. No spam; unsubscribe anytime.

What we cover

  • Aquatic strength training: strength, muscle, resistance and progressive overload in water
  • Aquatic exercise science: drag, buoyancy, density and hydrostatic pressure
  • Recovery and joint health: low-impact exercise, aquatic therapy and returning to activity
  • Healthy aging: strength, balance, mobility and independence
  • Exercise comparisons: where water beats land, and where it doesn't
  • Training methods and equipment: adjustable loading, water-filled equipment, progressive programs

The issues

  1. Introduction - Strength in Water® The Science
  2. Issue 1: Resistance Without Impact — Why Water Alone Doesn't Build Strength
  3. Issue 2: The Four Forces Working With You in Water
  4. Issue 3: Why Weight Behaves Differently in Water
  5. Issue 4: Recovery Isn't Just About Rest
  6. Issue 5: Progressive Overload in the Pool
  7. Issue 6: Speed and Shape — How Water Drag Changes Your Workout

Coming next, not yet published: Issue 7: Your Stance Is Part of the Exercise · Issue 8: A Useful Pool Routine Is One You Repeat · Issue 9: Strength and Cardio Can Share the Same Pool.

Research library and notes

These are the studies collected for Strength in Water®, including sources for upcoming issues. None tested AquaBLAST. Findings apply to the people and methods studied. Published issue references are linked; upcoming issue references will be linked when those articles are published.

Issue 6 research note: The Lopes review concerns drag in swimming. It did not test AquaBLAST. The hammer move is my practical training example, not a workout protocol tested by that review. Read Issue 6: Speed and Shape.

  • Gao Y, Deng W, Zeng Q, et al. Effects of aquatic exercise on improving body composition and muscle strength in the older adults: a systematic review and meta-analysis of RCTs. Front Public Health. 2026;13:1726568. doi:10.3389/fpubh.2025.1726568
    Discussed in: Issue 1 · Issue 4.
  • Jiang Y, Peng Y. Effects of aquatic rehabilitation on symptoms, physical function, and quality of life in individuals with knee joint dysfunction: a meta-analysis. Front Physiol. 2026;17:1804926. doi:10.3389/fphys.2026.1804926
    Discussed in: Issue 1 · Issue 2 · Issue 4.
  • Lopes TJ, Morais JE, Pinto MP, Marinho DA. Numerical and experimental methods used to evaluate active drag in swimming: a systematic narrative review. Front Physiol. 2022;13:938658. doi:10.3389/fphys.2022.938658
    Discussed in: Issue 2 · Issue 6.
  • Zheng S, Wang S, Cao Q, Li H. The impact of aquatic training on athletic performance and physical recovery in competitive athletes: a meta-analysis. J Strength Cond Res. 2026;40(6):723–737. doi:10.1519/JSC.0000000000005469
    Discussed in: Issue 3.
  • The role of aquatic training in improving risk of falls in older adults: a systematic review with meta-analysis and meta-regression. J Aging Phys Act. 2026. doi:10.1123/japa.2025-0083
    Discussed in: Issue 5.
  • Deng Y, Tang Z, Yang Z, Chai Q, Lu W, Cai Y, Luo Y, Zhou Y. Comparing the effects of aquatic-based exercise and land-based exercise on balance in older adults: a systematic review and meta-analysis. Eur Rev Aging Phys Act. 2024;21:13. doi:10.1186/s11556-024-00349-4
    For upcoming Issue 7, not yet published.
  • Martínez-Rodríguez A, Cuestas-Calero BJ, García de Frutos JM, Yáñez-Sepúlveda R, Marcos-Pardo PJ. Effect of aquatic resistance interval training and dietary education program on physical and psychological health in older women: Randomized controlled trial. Front Nutr. 2022;9:980788. doi:10.3389/fnut.2022.980788
    For upcoming Issues 7 and 9, not yet published.
  • Wang Y, Zhao J, Gao M, Wu X. Optimal dose of aquatic exercise for improving muscle strength in older adults: a Bayesian model-based meta-analysis. Front Public Health. 2025;13:1699018. doi:10.3389/fpubh.2025.1699018
    For upcoming Issue 8, not yet published.
  • Bunæs-Næss H, Kvæl LAH, Nilsson BB, Heywood S, Heiberg KE. Aquatic high-intensity interval training (HIIT) may be similarly effective to land-based HIIT in improving exercise capacity in people with chronic conditions: a systematic review and meta-analysis. BMJ Open Sport Exerc Med. 2023;9:e001639. doi:10.1136/bmjsem-2023-001639
    For upcoming Issue 9, not yet published.

Get each new issue by email

One research-backed issue every two weeks, plus pool workouts you can try. No spam; unsubscribe anytime.

Get each new Strength in Water® issue by email. One research-backed issue every two weeks, plus pool workouts you can try. No spam; unsubscribe anytime.

Aquatic Fitness Guide · Pool Exercise Equipment for Seniors · Why I Invented AquaBLAST

Strength in Water® is a registered trademark of Roma Consulting LLC.

FAQs

Below FAQ are some common concerns of our clients before purchasing AquaBLAST, if you have other questions, please just send it to info@aquablastfit.com.
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  • IMPORTANT INFORMATION
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IMPORTANT INFORMATION

AquaBLAST is a water-filled fitness bag that offers up to 55 lbs of water weight. It can also be used for low-impact aqua kickboxing in the pool.

I started working out in my swimming pool with 1-gallon milk jugs after injuring my rotator cuff playing softball. Underwater, the jugs gave me drag and resistance; lifting them above the water provided up to 8 lbs of weight. One day, I punched a jug floating past me and realized there was more to the idea. By adjusting the air, water, and a small counterweight, I could keep it neutrally buoyant and flexible enough to punch and kick. I kept tinkering with a weightlifting device for the pool until it became AquaBLAST, combining variable, progressive resistance with full-on aqua kickboxing, no martial arts training needed.

As Henry Ford famously said, “you can get a Model T in any color so long as it is black.”
Black is the only color we offer currently. We are considering additional colors in the future. Drop us a line and let us know what color you are interested in, and we will consider it for future production.

AquaBLAST is safe. We use PVC that is compliant with California Proposition 65, meaning that the materials in AquaBLAST comply with California’s strict requirements for the reduction of carcinogens. .

Once you fill it with air and water, you punch, kick, push, and lift the bag. Use AquaBLAST for fitness, low-impact exercise, and fun in the water..

Absolutely! However, AquaBLAST is not a floatation device, and parental supervision is always recommended when children are using the bag. Because AquaBLAST floats, it can easily drift into deeper water.

Empty, AquaBLAST weighs just 4 pounds

When filled with water AquaBLAST weighs between 40-50 pounds (depending on model) because it is filled with 5-6 gallons of pool water. Each gallon of water weighs about 8 pounds. When you lift the bag above water, gravity kicks in and you feel the weight.
Underwater AquaBLAST is at equilibrium with the surrounding water, so it is a lot easier to move around, but you still have the weight of water, but no gravity.

Keep the zipper lubricated so it opens and closes smoothly. If it becomes difficult to move, lubricate it rather than forcing it, which can put unnecessary stress on the zipper and finger pulls. Use silicone lubricant or food-safe silicone faucet grease from a hardware store. Crisco shortening is another option. If you don’t have silicone lubricant, email me (info@aquablastfit.com) and I’ll send you a tube. After filling the bag, pull the zipper firmly into its fully closed position without forcing it. Then gently squeeze the bag and check for leaks around the zipper.

Yes. Let some air out first, then place your foot on the bag and push it down to the pool floor. Once it’s in position, you can perform step-ups and log rolls. You can also try balancing on one foot.

YOUR INFORMATION

AquaBlastFit adheres to the highest industry standards to protect your personal information when you checkout and purchase from our online store.
Your credit card information is encrypted during transmission using secure socket layer (SSL) technology, which is widely used on the internet for processing payments. Your credit card information is only used to complete the requested transaction and is not subsequently stored.

We accept many forms of payment, including PayPal and the following credit cards: Visa, Mastercard, Discover, American Express..

You can cancel your order within 24 hours of placing it. After that, it will have been processed, and you won’t be able to cancel. You can, however, return your items for a full refund.

SHIPPING

Yes, we ship internationally. Shipping availability and costs are shown at checkout.

We choose USPS, UPS, DHL and other shipping carriers worldwide. We will select the best carrier for specific countries to make sure your package arrives in time.

Once payment has been made, 99% of all orders leave our fulfillment center within 2-3 days.

We are shipping from Mukilteo, Washington. Our average shipping time is up to 7 business days depending on your location. Once we approve international shipping, we expect the following delivery times: Canada, United Kingdom, Australia, and New Zealand: 7-20 business days. European countries: 7-25 business days. Asian countries: 7-25 business days. Rest of the world: 7-30 business days.

DELIVERY

We will send you the tracking number after your purchase within 1-3 business days. Please visit this link below to track your order.

It depends on the products you ordered. Since we may operate multiple fulfillment centers, sometimes your items may come with different packages.

RETURNS

You are fully covered and protected by our 30-day money back guarantee. All sales of reconditioned items are final, and cannot be returned.

If there’s some sort of manufacturing defect, let us know within 90 days of receiving your item, and we’ll send you a replacement or issue you a refund.