When people list their top performance supplements, they tend to reach for creatine, beta-alanine, BCAAs. Salt rarely makes the list. Dr. James DiNicolantonio — bestselling author and cardiovascular research scientist who has co-authored more than 300 academic papers — argues this is a significant oversight. Not because salt is superior to these compounds in principle, but because the research suggests it outperforms them by a substantial margin in practice.
This conversation covers three interlocking protocols: salt and hydration as ergogenic tools, sauna as a heat adaptation stimulus, and the foundational role of resistance training for longevity. Together, they form a practical framework for extracting more from every training session — and building a body that sustains itself over decades.
The biggest adaptation that endurance training produces in the body is an increase in blood volume. Elite male athletes carry roughly 7 litres of blood — compared to the average adult's 5 litres. Elite rowers can exceed 9 litres. This expanded volume is not incidental to their performance: it is central to it.
Here's why. Within five minutes of beginning vigorous exercise, blood volume drops by approximately 8–10%. Fluid is being pulled out of circulation to produce sweat for cooling and to serve working muscles. If you start with a depleted or average blood volume, you hit that drop fast. If you've preloaded, you have more to work with before the decline becomes limiting.
The mechanism is blood volume expansion through sodium and fluid retention. When you consume salt with adequate water in the right ratio before exercise, your body holds onto more plasma — increasing cardiac output, improving heat dissipation, enhancing nutrient delivery to muscle, and accelerating clearance of metabolic byproducts like hydrogen ions that drive the burning sensation of intense effort.
For everyday training, DiNicolantonio suggests approximately 1,000mg of sodium with 10–16oz of fluid in the period before exercise. For high-intensity sessions or competition, the evidence supports a more deliberate preload: 3,000–4,300mg of sodium with 26–34oz of fluid.
The concentration matters. Counterintuitively, a slightly hypertonic solution — marginally saltier than blood — appears more effective than matching blood salinity exactly. The body retains this fluid more completely, producing a larger and more stable volume expansion before exercise begins.
He also makes a nuanced point about timing and adaptation. Not every session should involve maximal preloading. Allowing mild dehydration to develop during training sessions over time actually drives blood volume adaptation in its own right — a form of osmotic stress that signals the body to expand plasma volume as a protective response. The heavy preload is reserved for competition and genuinely hard training days.
Sauna use produces a set of physiological adaptations that translate directly to exercise performance — adaptations that closely parallel those produced by endurance training itself.
Two weeks of daily sauna sessions produce measurable changes. First, baseline core body temperature drops. This sounds counterintuitive but is mechanistically important: a lower resting temperature means a larger thermal buffer before you hit the critical threshold where heat-sensitive enzymes begin shutting down ATP production. You can train harder, longer, before the heat becomes limiting.
Second, sweat composition changes. A heat-adapted body sweats more dilutely — losing less sodium and electrolytes per unit of fluid expelled. This is conservation, not depletion. The body learns to cool itself more efficiently, protecting the very electrolyte balance that underpins performance.
The practical implication: sauna sessions in the weeks before an event or a hard training block function as thermal preconditioning. The adaptation compounds with regular use, and the benefits carry over into performance even when the sauna sessions themselves cease temporarily.
Against the backdrop of blood volume and heat adaptation, DiNicolantonio is unambiguous about one thing: resistance training is the most important single modality for long-term health. Not because it produces the most dramatic short-term cardiovascular improvements — it doesn't — but because muscle mass is the primary defence against sarcopenia, the age-related loss of muscle and strength that underlies frailty, fractures, and early mortality.
Three to four sessions per week of 30–60 minutes is his baseline recommendation. The programme does not need to be complex. The commitment does need to be consistent. Muscle is expensive tissue to maintain — metabolically demanding, requiring continuous signalling to preserve — and the body will economise ruthlessly if that signal is not provided.
Performance is not only about effort and recovery. It is also about the substrate your effort works with. Blood volume, thermal regulation, and muscle mass are three of the most consequential variables in that substrate — and all three are trainable, through means most people have yet to fully explore.