The machines took the heavy lifting

In western Kenya, it is not unusual to see a Luo woman walking to market with a load on her head that weighs as much as 70 percent of her own body. Kikuyu women carry theirs on the back, from a strap across the forehead. Nobody calls it training. It is how the water, the firewood and the harvest get home.

01

Life used to load you.

For almost all of human history, people carried water, firewood, food and children. They dug, chopped, built and hauled. Nobody went looking for exercise, because the work of staying alive put load on every muscle they had.

Then we handed that work to machines. The car carries us, the lift climbs the stairs, the trolley takes the shopping and the van brings it to the door. Nobody wants the old kind of hard labour back. But it means our muscles now get almost no heavy work.

02

Endurance training does not build strength.

You run, ride or swim for hours every week. That builds the engine: the heart, the lungs, and muscles that can keep working for a long time. But it works your muscles many thousands of times against a light load, and strength is built by a heavy one. If nothing in your week is heavy, you stay as strong as you are, and from middle age you get weaker. Adults lose about four to five percent of their muscle every ten years, and their strength goes faster still.

03

Strength puts more into every stride.

Every stride, pedal stroke and swim stroke is your muscles pushing against something. Stronger muscles push with less effort, so each one costs you a little less.

In one study in Norway, well-trained runners added heavy half squats to their training three times a week for eight weeks. They became five percent more economical: running at the same pace now took five percent less oxygen. At their top aerobic speed, they could keep going 21 percent longer before they had to stop. A review of the best trials in highly trained runners found a large gain in economy too.

Five percent sounds small. But you take it with you into every stride, and a marathon is tens of thousands of strides. A long ride is tens of thousands of pedal strokes. The saving is paid out on every one of them, and it adds up over the hours.

In one study, eight weeks of heavy squats made well-trained runners five percent more economical.

04

It makes you faster.

The same holds on the bike. Well-trained cyclists who added heavy strength work twice a week for 12 weeks could hold more power in a 40-minute all-out effort. Cyclists who only rode showed no clear gain. In Finland, endurance athletes who swapped a third of their training for jumps and fast strength work ran 5 kilometres faster after nine weeks, and their sprint got quicker too.

These are not one-off results. A review of 24 studies of distance runners found that strength training generally improved economy by two to eight percent, and tended to improve race times and sprint speed. A review of runners and cyclists found the same pattern. Most of this research is on running and cycling. Swimming, skiing and hiking ask the same of your muscles: push, again and again, for hours.

05

It keeps you training.

Strength also keeps you in one piece. In a review of 25 trials in many sports, the strength programmes cut injuries to less than a third. Stretching on its own did not prevent them.

An injury costs you weeks. Strong muscles and tendons take the load of thousands of landings, hills and pedal strokes, so more of your training reaches race day. And when you tire late in a long effort, a strong body holds its shape instead of sagging into it. That is the posture that keeps you moving well in the last hour.

06

There is no downside.

The worry most endurance athletes have is weight. It does not happen. The runners in Norway gained no weight. The cyclists built bigger thigh muscles without getting any heavier. The review of 24 studies found that body composition was not harmed. Their aerobic engine was not harmed either.

A stronger athlete is a better athlete, all else being equal. And all else is not equal, because strength improves almost everything else: economy, speed, and how much training you can absorb without getting hurt.

07

Strength is the whole body, firing as one.

When you run, the push starts at your foot on the ground. It travels up through your ankle, knee and hip, through your trunk, and out to your swinging arms. On the bike, your trunk holds still so your legs have something to push from. In the water, the pull of your arm only moves you if your trunk and hips pass it on. No muscle works alone. The strength that matters is your whole body working together, at the same moment, in one movement.

That is why we do not train strength on machines. A machine holds you in a seat and moves one joint along a fixed track. It makes one muscle stronger, but it never asks your body to pass force from the ground to your hands, or to hold its shape while it does. Out on the trail or the road, nothing holds you in a seat.

08

Train it heavy, and with your whole body.

Physical work used to fill the day, and it was always whole-body work. Carrying water, digging a field, lifting a log or a stone: each one loads you from your feet to your hands at once. Nobody has the whole day for that now, so strength has to be trained on purpose, and efficiently. Most of the studies above used two or three short sessions a week. They used barbells and gym machines, because those are easy to measure in a lab. What we take from them is the heavy load, not the machine.

It also has to be heavy. A light weight lifted many times is more endurance, and you already have plenty of that. Strength comes from real effort: a load heavy enough that a few repetitions are all you have, or a movement done as fast as you can.

Sprinting is one of the best ways to get it. A hard sprint up a hill asks your legs and hips for nearly everything they have, and every part of you has to fire at once to give it. A few short sprints, with full rest between them, are strength training, not cardio.

Our main tool is the kettlebell: a heavy iron ball with a handle. You swing it, carry it, drive it overhead with your legs and lift it from the floor to standing. Every one of those is a whole-body movement, and none of them works one muscle on its own. In one study, young men did 12 minutes of kettlebell swings twice a week for six weeks. Their squat strength rose by almost 10 percent and their jump by almost 20.

And carry things again, the way the women of western Kenya never stopped doing. Take the shopping home in two heavy bags. Put a loaded pack on for a long walk. Dig the garden, move the stones, split the wood. It is the same strength, and the world is full of things to lift.

What this means for you

Daily life no longer makes you strong, and your endurance training builds the engine but not the strength around it. Yet strength is what makes every stride and every pedal stroke cheaper, makes you faster, and keeps you training.

So you have to train it yourself. You need strength training to keep your body capable of what it is supposed to do: to carry, climb, lift, pull and get back up, and to go further and faster than you could before. Train it heavy, with your whole body, two or three short sessions a week.

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