High-intensity interval training (HIIT) is one of the most time-efficient methods for improving cardiovascular fitness and burning calories. A typical 20-minute session can burn as many calories as 40 minutes of steady-state cardio, according to data published in the British Journal of Sports Medicine. But the standard HIIT exercises — burpees, box jumps, tuck jumps — produce significant impact noise, making them impractical in HDB flats where floor slabs are typically 15 to 20 centimetres thick.
This guide presents three apartment-friendly HIIT protocols that replace all jumping movements with low-impact alternatives while maintaining the metabolic demand that makes HIIT effective.
Understanding Noise Transmission in Singapore Apartments
Sound travels through building structures in two ways: airborne noise (voices, music) and structure-borne noise (footsteps, impacts). Jumping exercises generate structure-borne vibrations that travel through concrete floors and are amplified by the resonance of enclosed rooms below. The Building and Construction Authority (BCA) of Singapore sets minimum Impact Sound Class (ISC) ratings for new residential developments, but older HDB blocks built before 2014 often have minimal sound insulation.
The solution is not to avoid intensity — it is to eliminate the airborne phase of each movement. When at least one foot stays in contact with the floor at all times, impact forces drop by 60-80% compared to jumping movements. Heart rate elevation can still reach 85-95% of maximum through sustained muscle engagement and reduced rest periods.
Protocol 1: The 20-Minute Low-Impact Blaster
Perform each exercise for 30 seconds, rest for 15 seconds. Complete 4 rounds with a 60-second break between rounds.
Exercise List
1. Fast Step-Back Lunges (30 seconds, alternating)
Step one foot back into a lunge and immediately return. Alternate legs at a brisk pace — aim for 20-24 total repetitions. The rapid tempo elevates heart rate while the controlled foot placement keeps noise minimal.
2. Speed Squats (30 seconds)
Perform bodyweight squats at a pace of approximately one repetition per second. Touch the fingertips to the floor at the bottom of each squat to ensure full depth. The continuous movement without pauses creates a cardiovascular challenge comparable to running at moderate pace.
3. Push-Up to Shoulder Tap (30 seconds)
Perform a push-up, then at the top position, lift the right hand to tap the left shoulder. Alternate the tapping hand after each push-up. The anti-rotation demand forces the core to work harder, and the alternating pattern creates metabolic stress in the shoulders and triceps beyond what standard push-ups achieve.
4. Standing Bicycle Crunches (30 seconds)
Stand with hands behind the head. Bring the right knee up to meet the left elbow, crunching the obliques. Alternate sides at a brisk pace. This produces no floor impact and targets the obliques and hip flexors simultaneously.
5. Inch Worms (30 seconds)
From standing, fold forward and walk the hands out to a plank position, perform one push-up, then walk the hands back to the feet and stand up. Each repetition takes approximately 5-6 seconds. The full-body transition between standing and plank position drives heart rate upward efficiently.
6. Plank Jacks (Modified — 30 seconds)
In a plank position, step the right foot out wide, then the left foot out wide, then step them back together one at a time. This is the low-impact version of the traditional plank jack, which normally involves jumping the feet apart. The stepping version is silent while still engaging the inner thighs, hip abductors, and core stabilisers.
Protocol 2: Tabata-Style (16 Minutes)
Tabata intervals follow a strict format: 20 seconds of maximum effort, 10 seconds of rest, repeated 8 times per exercise (4 minutes per exercise). Complete 4 exercises for a 16-minute total session.
Exercise A: Fast Alternating Lunges — 8 rounds of 20 seconds on, 10 seconds off
Exercise B: Close-Grip Push-Ups — 8 rounds of 20 seconds on, 10 seconds off
Exercise C: Mountain Climbers (Slow, Controlled) — 8 rounds of 20 seconds on, 10 seconds off
Exercise D: Squat to Calf Raise — 8 rounds of 20 seconds on, 10 seconds off
The squat to calf raise is particularly effective: at the top of each squat, rise onto the balls of the feet for a two-second hold before lowering back into the next repetition. This adds a calf strengthening component and increases time under tension for the quadriceps.
Protocol 3: EMOM (Every Minute on the Minute — 20 Minutes)
Set a timer for 20 minutes. At the start of each minute, perform the prescribed number of repetitions. Use the remaining time in that minute as rest. As fatigue accumulates, rest periods naturally shrink.
- Minute 1: 15 bodyweight squats
- Minute 2: 10 push-ups
- Minute 3: 12 reverse lunges (6 per leg)
- Minute 4: 20-second plank hold + 5 slow mountain climbers per side
- Minute 5: 10 inch worms
Repeat this 5-minute cycle four times. By the third and fourth cycles, the repetitions become significantly more challenging due to accumulated fatigue — which is the mechanism that produces the EPOC (excess post-exercise oxygen consumption) effect responsible for continued calorie burning after the workout ends.
Optimising the Environment
A 6mm rubber exercise mat (available at Decathlon in Jurong East or online at Lazada for approximately S$20) absorbs residual impact from foot placement. Place it directly on the tile floor — not on carpet, which reduces stability during fast movements. Set air conditioning to 22-23°C before starting; HIIT generates substantial body heat, and the National Environment Agency notes that indoor temperatures in Singapore can exceed 30°C without active cooling, even with windows open.
A digital interval timer app eliminates the need to watch a clock. Free options include Tabata Timer (iOS/Android) and Interval Timer by Deltaworks. Pre-programming the work-rest intervals allows full focus on exercise form rather than time tracking.
Frequency and Combination with Other Routines
HIIT should not be performed daily. Two to three sessions per week, with at least 48 hours between sessions, allows the cardiovascular system and muscles to recover. On alternate days, a full-body strength routine or a morning stretching session provides a balanced weekly schedule. The World Health Organization recommends 75 minutes of vigorous-intensity aerobic activity per week — three 25-minute HIIT sessions meets this target exactly.
The effectiveness of HIIT is not determined by how much noise it generates. Impact noise is a function of how the body contacts the floor, not how hard the muscles are working. Replacing jumps with speed and sustained tension keeps the metabolic benefit while respecting shared living environments.
Safety Considerations
Anyone with pre-existing knee, hip, or cardiovascular conditions should consult a medical professional before starting HIIT. Polyclinics across Singapore (SingHealth, NHGP) can provide exercise clearance during routine health screenings. For beginners, starting with Protocol 3 (EMOM) at reduced repetition counts allows a gradual build-up to full intensity over two to three weeks.
