Walking Intensity Matters More Than Duration: The Copenhagen City Heart Study

Walking faster reduces mortality risk more than walking longer. The Copenhagen City Heart Study tracked 7,308 healthy adults aged 20 to 93 and found that walking intensity had a significant inverse association with all-cause mortality, while walking duration showed only a weak association. Hiko is built around this principle: intensity drives results.

The Study

The Copenhagen City Heart Study is a long-running cardiovascular epidemiological study based in Copenhagen, Denmark. The walking analysis, led by Peter Schnohr and published in 2007 in the European Journal of Cardiovascular Prevention and Rehabilitation (PubMed 17301630), examined 7,308 healthy women and men aged 20 to 93.

Participants were assessed at the third examination of the Copenhagen City Heart Study, conducted between 1991 and 1994. Researchers recorded self-reported walking pace (slow, average, fast) and weekly walking duration, then followed participants over subsequent years to track all-cause mortality outcomes.

This was not a small pilot study. Over seven thousand participants across a 73-year age range makes this one of the most robust population-level analyses of walking and mortality ever conducted. Hiko takes these findings seriously because the evidence base is large enough to draw real conclusions.

The Core Finding — Intensity Beats Duration

Schnohr’s analysis produced a clear hierarchy: walking pace had a significant inverse association with all-cause mortality. Walking duration had only a weak inverse association.

In practical terms: a person who walks briskly for 30 minutes gets more mortality-reduction benefit than a person who walks slowly for 60 minutes. The pace at which you move matters more than how long you move.

This finding aligns with related research from the Copenhagen team. Schnohr et al. published in the Journal of the American College of Cardiology (JACC) in 2015 showing that 1 to 2.4 hours of jogging per week at a slow or average pace was associated with the lowest mortality — reinforcing that moderate-to-high intensity at reasonable volumes outperforms low intensity at high volumes.

A 2014 study by Andersen et al. in PLOS One, also drawing on the Copenhagen City Heart Study data, found that walking pace was associated with reduced heart failure risk. The pattern is consistent across endpoints: pace drives outcomes. Hiko structures every workout around this evidence.

What This Means for Rucking

Rucking adds a load to your back, which increases the metabolic cost of every step. This is a built-in intensity amplifier. Even at a moderate walking pace, carrying 10 to 20 kilograms elevates your energy expenditure significantly above unloaded walking at the same speed.

The Copenhagen study measured self-reported walking pace, not metabolic intensity directly. But the underlying mechanism is energy expenditure per unit of time. Rucking achieves elevated energy expenditure without requiring you to walk faster — the load does the work of increasing intensity.

This means ruckers may access the mortality-reduction benefits associated with brisk walking even at moderate paces. Hiko quantifies this precisely using the LCDA equation from USARIEM, which calculates the metabolic cost of your specific body weight, load weight, speed, and grade every second.

Why Interval Walking Training Aligns with Copenhagen’s Findings

Interval Walking Training (IWT), developed by Professor Hiroshi Nose and Professor Shizue Masuki at Shinshu University, alternates between 3 minutes of fast walking and 3 minutes of slow recovery walking. The fast phase drives metabolic intensity well above the threshold that Schnohr’s study associated with reduced mortality.

Professor Masuki’s 2019 Mayo Clinic Proceedings paper identified high-intensity walking time as the key determinant of IWT health benefits. This maps directly onto the Copenhagen finding: it is the intensity of effort, not total time spent walking, that predicts outcomes.

IWT also solves a practical problem that the Copenhagen data implies. If brisk walking is protective but sustained brisk walking is difficult for older or less fit adults, then structured intervals offer a way to accumulate high-intensity minutes with built-in recovery. Hiko guides you through every interval phase so you spend enough time in the fast phase to matter.

How Hiko Applies This Science

Hiko combines the Copenhagen study’s core insight (intensity over duration) with two complementary research programs:

• IWT from Shinshu University: Structures your walk so you accumulate high-intensity minutes through 3-minute fast intervals, with slow recovery between them
• LCDA from USARIEM: Calculates the exact metabolic cost of your load, speed, and terrain every second, so you know your actual intensity — not an estimate

When you ruck with IWT intervals in Hiko, you are stacking two intensity multipliers: the load on your back and the fast walking phases. Hiko tracks both simultaneously and shows you real-time calorie expenditure that reflects the combined effect.

The Copenhagen study told us what matters. Shinshu University told us how to structure it. USARIEM told us how to measure it. Hiko puts all three together.

Frequently Asked Questions

Does walking pace really matter more than duration?

Yes. The Copenhagen City Heart Study (Schnohr et al. 2007, European Journal of Cardiovascular Prevention and Rehabilitation) found that walking intensity had a significant inverse association with all-cause mortality in 7,308 adults, while walking duration showed only a weak association. Hiko prioritizes intensity tracking for this reason.

How does rucking increase walking intensity?

Carrying a load increases the metabolic cost of every step. The LCDA equation used by Hiko calculates that a 80 kg person carrying a 15 kg pack at 5 km/h on flat ground expends meaningfully more energy than the same person walking unloaded. The load acts as a built-in intensity amplifier without requiring you to walk faster.

What walking pace reduces mortality risk?

The Copenhagen study found that brisk (fast) walking pace was associated with the greatest reduction in all-cause mortality. The related jogging analysis (Schnohr et al. 2015, JACC) found that slow-to-average jogging pace at 1 to 2.4 hours per week showed the lowest mortality. Both findings point to moderate-to-high intensity at reasonable volumes as optimal. Hiko helps you maintain the right intensity through IWT interval guidance and real-time metabolic tracking.

How does Interval Walking Training relate to the Copenhagen findings?

IWT’s 3-minute fast intervals push you into the high-intensity walking zone that the Copenhagen study associated with reduced mortality. Professor Masuki’s 2019 research confirmed that high-intensity walking time is the key determinant of health improvements from IWT. The protocols are independently developed but scientifically aligned.