VO2 max—how much of it is genetics and how much is trainable?

In this thread, I’ll discuss a long-running debate about whether or not everyone “responds” to exercise training. 👇🏼🧵 Current public health guidelines recommend moderate to vigorous aerobic physical activity for around 150-300 minutes each week.

Studies have shown an average increase in VO2 max ranging from 15% to 20% can occur through guidelines-based exercise programs.

However, more frequent or intense training can lead to even higher increases in VO2 max, averaging around 25% to 30%.

This suggests that individuals of various backgrounds and fitness levels can experience improvements in VO2 max through training, though certainly at the highest levels of fitness, there is less room for improvement.

What determines VO2 max?

And what are its limiting factors?

The primary factors can be classified as:

Central factors 🫀

- pulmonary diffusing capacity
- maximal cardiac output
- oxygen-carrying capacity of the blood

Peripheral factors 🦵🏼

- skeletal muscle characteristics

Read on to learn more 🧵👇🏼 Lungs

The pulmonary system (the lungs) can limit VO2 max under certain circumstances:

- exercising at moderately high altitudes
- people who have asthma or other chronic obstructive pulmonary diseases. 

Trained individuals with an extremely high cardiac output may undergo arterial oxygen desaturation during maximal exercise — the blood moves too quickly through their pulmonary system to become fully saturated with oxygen.

The ability to increase exercise capacity in individuals with pulmonary limitations shows the presence of a pulmonary limitation to VO2 max, however, the lungs don’t appear to be a limiting factor in trained individuals or people without pulmonary diseases.

Breathing hyperoxic air (air that contains more oxygen than normal) doesn’t increase VO2 max in normal people, but it does in highly trained athletes (in whom a pulmonary limitation might be present due to the abovementioned factors).

Exercise volume or intensity: which is more important for promoting training adaptations? 🫀🫁

A recent meta-analysis explores this question & provides evidence on how training variables influence mitochondrial content, capillarization, and VO2 max.

Let’s explore. 👇🏼 The main focus was on the comparison between different training intensities, which the authors defined as:

- Low- and moderate-intensity continuous endurance training: an intensity below the second ventilatory threshold, 4 mmol/L blood lactate, 87% of maximal heart rate, 87% of VO2 max, or 75% of Watts max.

- High-intensity interval or continuous training: an intensity above the second ventilatory threshold, 4 mmol/L blood lactate, 87% of maximal heart rate, 87% of VO2 max, or 75% of Watts max.

- Sprint interval training: protocols involving maximal or supramaximal efforts lasting 4–90 seconds.

Marathon training W1/D1

10 miles easy
Marathon training W1/D2 (part I)

- 6-mile tempo run @ goal marathon pace

- 4-mile warmup and 2-mile cooldown

⏱️: 5:38, 5:41, 5:38, 5:33, 5:36, 5:34

Super pleased with today. The effort was very manageable despite heat and humidity.

First part of today’s double threshold session. Trying something new and might run again (shorter) this afternoon.

High-intensity interval training for plaque reduction 🫀

Is HIIT safe and effective for people with heart disease?

🧵 Exercise is a wonder drug for cardiovascular disease (CVD) prevention and reversal.

One of the biggest risk factors for CVD development is the buildup of plaque in the coronary arteries (the arteries surrounding the heart that provide it with its own blood supply).

The best time of day to exercise for health ⏰

Should you workout in the morning or the afternoon to maximize the metabolic benefits?

A 🧵 Clinically, about 1/3 of adults have metabolic syndrome — a cluster of conditions including abdominal obesity, high blood pressure, high blood glucose, high triglycerides, and low HDL cholesterol.

Resistance exercise for cardiovascular health 🫀

The AHA just dropped a new Scientific Statement on the benefits of strength training.

You're going to want to bookmark this.

🧵
Epidemiological evidence 🌎

Adults who participate in RT have nearly a 15-17% lower risk for all-cause and CVD mortality vs. adults who report no RT.

The maximum risk reduction occurs at 30-60 minutes/week.

Despite this, only 28% of US adults participants in RT 2 days/week.

Endurance exercise and atherosclerosis

Is working out too hard detrimental to heart health?

🧵
There’s no better way to improve your chances of aging gracefully and reduce your risk of major noncommunicable diseases than to get adequate levels of physical activity.

Exercise is great for blood glucose control.

Is there a “best” time to exercise to obtain the most benefit?

A 🧵 Blood glucose and insulin sensitivity exhibit a diurnal rhythm — glucose tolerance is better in the morning compared to the afternoon and the evening.

Glucose levels are lowest around the midpoint of our sleep. In people with impaired glucose tolerance or type 2 diabetes, the nadir in nighttime glucose is followed by a rise in glucose between 3 and 9 a.m.; this is referred to as the dawn phenomenon and occurs due to the body increasing its glucose production (referred to as endogenous glucose production).

Time-restricted eating vs. calorie counting for weight loss.

Does fasting have unique benefits? Or is it all about "calories in, calories out"?

Check the link in my bio for an in-depth post.

Keep reading for a🧵
Fasting has several well-regarded benefits, and though many of them have only been studied in animal models to date, evolutionarily conserved processes that we share with our non-human relatives suggest that these benefits may also apply to us.

Strength training vs. endurance training for healthy aging

As we get older, muscle fiber type changes, strength declines, and neuromuscular atrophy occurs.

Are lifelong athletes protected? And what's the best type of exercise to counteract aging?

A thread 🧵
Aging is typically accompanied by declines in maximal strength, force-generating capacity, and muscle mass.

This loss of size and strength occurs primarily in type II (“fast-twitch”) muscle fibers, resulting in an increase in the proportion of type I (“slow-twitch”) fibers.

Caffeine, genes and exercise performance. ☕️

Caffeine is one of the most well-studied ergogenic aids ever - and also one of the most (legal) effective ones.

Let's talk about how caffeine improves performance and the role of genes.

Thread 🧵
Exercise physiologist Dr. David Costill made significant contributions to the study of caffeine and exercise performance. His research played a pivotal role in understanding the effects of caffeine during exercise.

Nose breathing for heart health. 🫀

There are claims that nasal-only breathing is superior to mouth breathing.

How does their physiology differ? And does nose breathing really produce beneficial effects on the body?

Thread. 🧵
Nasal breathing warms, humidifies, and filters air; it also leads to greater production of nitric oxide (NO) in our airways, enhancing vasodilation.

In addition, when we breathe through our nose, we use our diaphragm, lowering the metabolic cost of breathing.

🧵

If you’re trying to improve your aerobic capacity, what’s the best way to do it?

High intensity intervals? Lactate threshold runs? Long slow endurance training?

Here are the top protocols to optimize VO2 max 👇🏼 Aerobic base building (low- to moderate-intensity training) is an important aspect of all training programs. ⛰️

But if you’re interested in increasing cardiorespiratory fitness (VO2 max), there seems to be a clear winner in terms of which intensity is best.

If you’re trying to practice nasal breathing during endurance/cardio or a strength session, let me introduce you to a tactic I’ve tried once or twice.

It sounds crazy (and intense), buts it’s literally zero cost and incredibly effective.

The “mouthful of water run.” This tactic was apparently practiced by the Apache tribes—who were well-known for their stamina and endurance ability.

Ala the Tarahumara tribes profiled in the book “Born to Run”.

What is the "sweet spot" of aerobic exercise to improve longevity?

In the Copenhagen Heart Study (academic.oup.com/aje/article/17…) male and female joggers lived, on average, 6 years LONGER than non-runners.

But which levels of exercise provided the most benefit? Those running between 1-2.5 hours per week seemed to gain the greatest survival advantage vs. non-runners.

Running >2 hours per week actually erased this survival advantage -- more exercise provided no survival advantage vs. the non-runners.

Yesterday, @foundmyfitness tweeted a study showing a 28% increase in VO2 max and an 18% increase in grip strength after 60 days of Vitamin D supplementation.

Sounds too good to be true, right?

Maybe it is. Let's discuss (thread) 👇

https://twitter.com/foundmyfitness/status/1498381154419892231?s=20&t=QB8vfRVH7ERKUv3wViJFLQ

Study: Association of Vitamin D Supplementation in Cardiorespiratory Fitness and Muscle Strength in Adult Twins: A Randomized Controlled Trial journals.humankinetics.com/view/journals/…

Yesterday, I “finished” my third round of physical therapy in the past 2 years.

t’s been a “miserable” 2 years of clawing my way back to running, each time to only get sidelined another injury.

But I’ve learned a few things (thread) 1. Running isn’t everything

It’s a lot of things to me, and always will be. Running is pure, meditative, and honestly one of the largest sources of joy in my life.

But can I live without it? Yes. I’ve had to...

Why we got fat - a nice vox article with charts, to help us see that there is no ONE explanation for the epidemics of diabetes/obesity

vox.com/2016/8/31/1236… #1 - We eat out - a lot (TOO MUCH)

2015 - Americans spent more money eating away from home than they did on groceries. People typically consume 20-40% more calories in restaurants vs. at home