The Rundown

Fit Is Better Than Thin. Researchers at the University of Virginia say that it’s time to shift perspectives on the relationship between fitness and body fat and start looking at the value of a fitness-based approach rather than a weight-loss approach in optimizing health outcomes.

Their recently published work found that cardiorespiratory fitness is a stronger predictor of both cardiovascular disease and all-cause mortality than body mass index (BMI). As one of the study’s authors puts it, fitness is “far more important than fatness when it comes to mortality risk.”

The researchers reviewed twenty studies with a total sample size of more than 398,000 adults from multiple countries. In the majority of studies, people were classified as fit if their exercise stress test score (estimated or directly measured VO2max) put them above the twentieth percentile within their age group.

The study found that obese fit individuals had a similar risk of death to that of normal weight fit individuals and close to one-half that of normal weight unfit individuals. In other words, exercise can largely reduce the risk of cardiovascular disease and all-cause death for people of all sizes.

Take the Plunge? Cold water immersion has been extensively researched and used in sporting contexts to help athletes recover but less has been studied on its effects on the general population. Do daily cold plunges, whether in the form of a cold shower, swimming in frigid water or sitting in an ice-filled bathtub, benefit health and well-being? University of South Australia researchers used a meta-analysis to find out.

For their review, the scientists analyzed 11 studies published between 2014 and 2023, with a total of 3,177 healthy adult participants. Ten of the studies looked at immersion in an ice bath or cold plunge and one study examined the effect of cold showers. The participants were immersed in water at or above chest level and water temperature ranged from 45 -59 degrees Fahrenheit. The immersion times were at least 30 seconds and up to two hours.

The team noted a range of time-dependent results. They found that cold-water immersion could reduce stress levels, but only for around 12 hours post-exposure. Participants who took thirty, sixty or ninety second cold showers for one month reported higher quality of life scores but these effects faded after three months.

They also found some links to cold-water immersion and better sleep outcomes but that data was restricted to males, which limits its broader application. There was very little evidence to support claims that cold-water immersion can boost immunity and mood.

Taking the plunge was associated with a significant increase in inflammatory markers immediately and an hour after immersion. While this sounds counterintuitive, it is the body’s reaction to the cold as a stressor and helps it adapt and recover, similar to how exercise causes muscle damage before making muscles stronger.

The researchers note that for elite athletes, the process helps to reduce inflammation and muscle soreness after exercise but for people with pre-existing conditions, the initial inflammation from cold-water immersion could have detrimental health impacts and they should take extra care if participating.

Tara Cain, lead author, sums up the study results this way, “Right now, there isn’t enough high-quality research to say exactly who benefits most or what the ideal approach is to cold-water immersion.”

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The Latest Fitness Tech. January’s Consumer Electronics Show is known for weird and wonderful fitness tech and this year’s installment was no exception. Here are a few highlights:

Garmin announced the Garmin Instinct 3, the third iteration of its popular outdoor smartwatch, promising that its new-to-the-range solar technology offers five times more battery life than the Instinct 2 Solar. It also has a more rugged design, a flashlight and the addition of Garmin Pay.

The Circular Ring 2 features an Atrial Fibrillation detection algorithm that is FDA-approved, a first in the market. The ring can be sized using a smartphone camera and an app, rather than a plastic sizing kit.

A stylish addition to the AI powered home gym market, the amp fitness machine features adjustable cable machine weights, a camera, and a companion app for workouts that will adapt in real-time.

Suunto Aqua waterproof headphones have IP68 waterproofing, 32GB of onboard storage and ten hours of battery life. While the headphones can be used outdoors for cycling and running, swimming is where it really shines and swimmers can take advantage of an AI-powered coach that can track metrics like stroke posture, head pitch angle, breath frequency and glide time.

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Court of Gold. This documentary covers the Paris Olympics’ men’s basketball tournament, with four separate production teams each assigned to the U.S., Canada, Serbia and France. Players including Steph Curry, Kevin Durant, France’s Nicolas Batum, Serbia’s Bogdan Bogdanović and Canada’s Dillon Brooks go deep with the filmmakers to create what one critic is already calling the year’s “best sports documentary.” Court of Gold is streaming now on Netflix.

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Stronger By Science. While it aired its final episode last year (and was mentioned many Fit Cult newsletters ago), this podcast is worth another recommendation for its exploration of evidenced-based scientific principles. Each episode dives into exercise and nutrition research, health and fitness trends and listener questions.

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Is ‘Zone 2’ the Magic Effort Level for Exercise? In this piece for the New York Times, Alex Hutchinson gives a mini-tutorial on what Zone 2 training is and what the science says about it.