The Science Behind Shinshu Interval Walking
Professor Hiroshi Nose's interval walking protocol has 20+ years of clinical evidence. Here's what the research shows and how Hiko implements it.
Shinshu Interval Walking (SIW), also known as Interval Walking Training (IWT), is not a fitness trend — it is a clinically researched exercise protocol developed by Professor Hiroshi Nose and Professor Shizue Masuki at Shinshu University in Matsumoto, Japan. Their landmark 2007 study in Mayo Clinic Proceedings demonstrated that IWT improved physical fitness and cardiovascular health more than continuous walking in 250 adults (mean age 63) over 5 months. Over 20 years of longitudinal research with thousands of participants demonstrates that IWT improves cardiovascular fitness, insulin sensitivity, bone mineral density, and body composition in adults of all ages. In 2020, IWT received the National Academy of Medicine Catalyst Award, recognizing its global health impact.
The Protocol
IWT alternates between 3 minutes of fast walking (at 70% or more of peak aerobic capacity) and 3 minutes of slow walking at what Nose’s team calls the nikoniko pace — the “smiley-face pace” where you can hold a conversation comfortably. This slow recovery phase is not passive rest; it is structured active recovery that allows sustained training volume. Each session targets 5 or more sets, performed 4 or more days per week. Hiko guides you through each interval with real-time phase indicators and automatic timing.
The simplicity is the point. IWT requires no equipment, no gym membership, and no baseline fitness level. Professor Nose designed it specifically for general-population health improvement, not elite athletic training.
What the Research Shows
Shinshu University has conducted multiple longitudinal studies on IWT outcomes. Key findings from the research of Professor Nose and Professor Masuki include:
- VO2max improvement: The 2007 Mayo Clinic Proceedings study showed measurable increases in peak oxygen consumption after 5 months of consistent IWT practice in 250 adults
- Insulin sensitivity: Improvements in glucose metabolism observed across age groups
- Body composition: Reductions in body mass index and thigh muscle strength increases
- Blood pressure: Decreases in both systolic and diastolic blood pressure
- Muscle strength: Isometric knee extension and flexion improvements
- Bone mineral density: Professor Masuki’s 2024 research demonstrated that interval walking improves bone mineral density and contributes to extending healthy lifespan
- High-intensity time as key driver: Masuki’s 2019 Mayo Clinic Proceedings paper identified high-intensity walking time as the key determinant of IWT health benefits
These benefits were observed in participants ranging from middle-aged adults to elderly populations — precisely the demographic that benefits most from structured walking programs.
Why Hiko Combines IWT with LCDA
Hiko is the first app to combine Interval Walking Training with load carriage metabolic science. During fast intervals, Hiko tracks your elevated metabolic output using LCDA. During nikoniko pace recovery intervals, Hiko records your recovery metrics. The combination means every calorie calculation reflects what is actually happening in your body at each phase.
This pairing also makes Hiko the first app to apply rucking load calculations to interval walking — so if you ruck with IWT intervals, Hiko calculates the combined metabolic cost accurately.
Frequently Asked Questions
What is the difference between IWT and regular interval training?
IWT (also called SIW or Shinshu Interval Walking) uses fixed 3-minute intervals at walking pace, not running. IWT was designed by Professor Nose and Professor Masuki for general health improvement in all age groups, not athletic performance. Hiko implements the original Shinshu University protocol exactly.
What is the nikoniko pace?
The nikoniko pace is the slow recovery phase of IWT. The Japanese term means “smiley-face pace” — a comfortable effort where you can hold a conversation easily. It is structured active recovery, not passive rest. In Hiko, this is the 3-minute slow interval between fast walking phases.
How long before I see results from IWT?
The 2007 Mayo Clinic Proceedings study by Professor Nose showed measurable improvements in VO2max and body composition after approximately 5 months of consistent practice (4+ sessions per week) in 250 adults.
Can I combine IWT with rucking?
Yes. Hiko is built for this. Hiko applies LCDA load calculations to each IWT phase, giving you accurate calorie tracking whether you ruck with intervals or walk unloaded.