Standing Leg Curl

The unilateral hamstring builder — trains each leg independently while developing balance, stability, and functional strength

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⚡ Quick Reference

Aspect	Details
Pattern	Hinge (Isolation)
Primary Muscles	Hamstrings
Secondary Muscles	Calves, Glutes
Equipment	Standing Leg Curl Machine
Difficulty	⭐ Beginner
Priority	🟠 Common

Movement Summary

Unique Advantages

• Unilateral (one leg at a time): Identifies and fixes strength imbalances
• Balance component: Functional stability training
• Standing position: More transferable to athletic movements
• Reveals asymmetries: Can't hide weak side

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🎯 Setup

Starting Position

1. Machine height adjustment: Pad should align with your lower calf/Achilles when standing
2. Pad position: Set arm length so pad rests just above ankle on the back of leg
3. Weight selection: Start with 40-50% of what you use for bilateral lying/seated curls
4. Support leg placement: Standing leg on platform, knee slightly bent
5. Working leg position: Behind you, pad against lower calf
6. Grip handles: Firmly but not white-knuckle — for stability
7. Posture: Upright torso, core engaged, slight forward lean acceptable

Equipment Setup Details

Component	Setting	Purpose	Common Mistakes
Pad height	Lower calf/Achilles area	Proper leverage	Too high = knee stress
Pad arm length	Comfortable extension behind you	ROM and comfort	Too far = balance issues
Platform	Stable, non-slip surface	Safety	Foot sliding = danger
Handle position	Chest height, easy to grip	Stability	Too high/low = poor posture

Machine Setup Variation

Standing leg curl machines vary significantly by manufacturer. Some have a pad that swings front-to-back, others have a rotating arm. Spend time adjusting to YOUR body dimensions — one size does NOT fit all.

Body Position Checklist

• Support leg on platform, slight knee bend
• Working leg positioned behind you, pad on lower calf
• Torso upright (or slight forward lean)
• Core engaged for stability
• Hands on handles, not pulling/pushing excessively
• Weight distributed through entire foot of support leg
• Ready to curl without shifting body position

Pre-Set Verification

Before your first rep, check:

1. Can you balance comfortably on support leg? (Should be YES)
2. Is working leg positioned naturally behind you? (Should be YES)
3. Can you curl without the machine pulling you backward? (Should be YES)
4. Do you feel stable? (Should be YES)

If any answer is NO, adjust machine or reduce weight.

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🔄 Execution

The Movement

🎯 Starting Position

What's happening: Single-leg balance with hamstring loaded

1. Standing on one leg, slight bend in knee
2. Working leg extended behind you
3. Pad against lower calf
4. Torso stable and upright
5. Core engaged
6. Already feeling hamstring tension

Breathing: Inhale, brace core

Feel: Balance engaged, hamstring ready to work

Critical: Establish solid balance BEFORE starting to curl

⬆️ Concentric (Curling) Phase

What's happening: Hamstring contracts to bring heel toward glute

1. Curl heel toward your buttock — pull with hamstring
2. Keep support leg stable (don't sway)
3. Maintain torso position — no excessive leaning
4. Hip of working leg stays in line with body
5. Continue until maximum contraction
6. Breathing: Exhale as you curl

Tempo: 1-2 seconds (controlled)

Feel: Isolated hamstring contraction on working leg, balance challenge

Cue: "Pull heel to butt, stay stable"

Common error: Leaning forward excessively or rocking body

💥 Peak Contraction

What's happening: Maximum hamstring shortening

1. Heel curled as high as possible
2. Squeeze hamstring hard — 1-2 second hold
3. Maintain balance on support leg
4. Don't let body twist or shift
5. Feel the intense contraction

Balance check: Can you hold this position without wobbling? Should be relatively stable.

Advanced: Pause 2-3 seconds for enhanced mind-muscle connection

⬇️ Eccentric (Lowering) Phase

What's happening: Controlled resistance while maintaining balance

1. Slowly lower the weight — resist the pull
2. Control for 2-3 seconds minimum
3. Maintain balance throughout
4. Don't let weight stack crash
5. Breathing: Inhale as you extend
6. Return to stretched position with slight knee bend

Tempo: 2-3 seconds (critical for strength and stability)

Feel: Hamstring lengthening under tension while maintaining balance

Challenge: Eccentric + balance = significant coordination demand

End position: Working leg extended behind you, ready for next rep

Key Cues

Primary Cues

• "Heel to glute" — clear target for the curl
• "Stay stable, don't rock" — prevents momentum
• "Balance on entire foot" — stability through support leg
• "Squeeze and hold at the top" — maximizes contraction

Secondary Cues for Common Issues

Issue	Cue	Fix
Body swaying/rocking	"Stay tall and still"	Reduce weight, engage core
Leaning forward excessively	"Chest up"	Upright torso, less weight
Support knee locking	"Soft knee on support leg"	Slight bend maintained
Hip hiking	"Keep hips level"	Control movement, reduce weight
Twisting	"Face forward, shoulders square"	Stability focus

Tempo Guide

Training Focus	Concentric	Peak Hold	Eccentric	Rest Between
Strength	1-2s	1s	2-3s	0s
Hypertrophy	1-2s	2s	3s	0s
Balance/Stability	2s	2-3s	3-4s	1s (reset)
Endurance	1s	0-1s	2s	0s

Unique Balance Component

The standing position adds functional challenge:

Standing leg curl requires:

• Core stability to prevent torso movement
• Hip stabilizers to maintain alignment
• Ankle stability on support leg
• Proprioception (body awareness in space)

This makes it more "functional" than lying/seated variations — better transfer to sports and daily activities.

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💪 Muscles Worked

Activation Overview

Primary Movers (Working Leg)

Muscle	Action	Activation
Hamstrings	Knee flexion — isolated to one leg	██████████ 95%

Hamstring Breakdown:

• Biceps Femoris (Long & Short Head): 95%
• Semitendinosus: 95%
• Semimembranosus: 95%

Secondary Muscles (Working Leg)

Muscle	Action	Activation
Gastrocnemius (Calves)	Assists knee flexion	█████░░░░░ 45%
Glutes	Stabilize hip, maintain position	████░░░░░░ 38%

Stabilizers (Both Legs + Core)

Muscle	Role	Activation	Leg
Core	Prevent torso rotation/movement	██████░░░░ 55%	Both
Hip Stabilizers	Maintain single-leg balance	██████░░░░ 60%	Support
Glutes (support leg)	Stabilize pelvis	█████░░░░░ 50%	Support
Adductors/Abductors	Prevent hip shift	████░░░░░░ 40%	Support
Quadriceps (support leg)	Maintain slight knee bend	███░░░░░░░ 30%	Support

Unique Stabilization Demand

Standing leg curls require significantly MORE core and hip stabilizer activation than lying or seated variations. This makes them excellent for functional strength and revealing imbalances, but also means you can't lift as heavy.

Unilateral Advantage

Training one leg at a time provides:

1. Identifies imbalances: Can't compensate with stronger leg
2. Fixes asymmetries: Forces weak side to do the work
3. Greater mind-muscle connection: Focus on one hamstring at a time
4. Functional strength: Single-leg stability transfers to sports/life
5. Prevents cheating: Bilateral exercises can hide weak sides

Expected strength difference:

• 5-10% difference between legs = normal
• 10-20% difference = notable imbalance, work on it
• 20%+ difference = significant asymmetry, prioritize correcting

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⚠️ Common Mistakes

Mistake	What Happens	Why It's Bad	Fix
Excessive body lean/rocking	Using momentum and torso to assist curl	Removes hamstring isolation, defeats purpose	Reduce weight, stay upright, focus on stability
Support knee locked	Standing leg completely straight	Joint stress, poor balance	"Soft knee" — maintain slight bend
Hip hiking	Lifting hip of working leg to "cheat" the curl	Not true hamstring work, poor form	Keep hips level, reduce weight
Twisting/rotating torso	Body rotates toward or away from working leg	Removes isolation, balance compromised	"Face forward," shoulders square
Partial range of motion	Not curling heel all the way to glute	Missing peak contraction benefits	Full ROM, reduce weight if needed
Too much weight	Can't maintain balance or control	Form breakdown, ineffective	Ego check — this is unilateral work, go lighter
Gripping handles too hard	White-knuckle death grip	Tension in arms/shoulders, compensating	Lighter grip, just for balance
Support foot positioning	Weight on toes or heel only	Balance issues, unstable	Entire foot on platform, distribute weight

Most Common Error

Using too much weight and compensating with body movement: Standing leg curls require less weight than bilateral variations. If you're rocking, leaning excessively, or losing balance, you're going too heavy. Drop the weight and focus on isolated hamstring contraction with stable body position.

Self-Check Checklist

• Maintaining balance on support leg throughout set
• Torso upright (or minimal forward lean, consistent)
• No rocking, swaying, or twisting
• Support knee maintains slight bend (not locked)
• Hips stay level (not hiking one side)
• Full ROM (heel to glute, controlled extension)
• Squeeze and pause at peak contraction
• Controlled eccentric (2-3 seconds)
• Feeling it primarily in working hamstring

Video Self-Assessment

Record yourself from the side:

• Does your torso position change during reps? (Should be minimal)
• Is your support leg stable? (Should be YES)
• Can you see full ROM in working leg? (Should be YES)

Record from behind:

• Do your hips stay level? (Should be YES)
• Does your body twist? (Should be NO)

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🔀 Variations

By Foot/Ankle Position

Neutral (Standard)

Position	Effect	Best For
Toes/ankle neutral	Balanced hamstring activation	Default starting position
Natural foot position	Comfortable, effective	Most people

Toes Flexed Up (Dorsiflexion)

Position	Effect	Best For
Toes pulled toward shin	Reduces calf involvement	Hamstring isolation, preventing cramps
Active ankle flexion	More isolated hamstring work	Those with calf cramping issues

Toe Rotation

Position	Effect	Emphasis
Toes out (externally rotated)	30-45° outward	Inner hamstrings (semimembranosus, semitendinosus)
Toes in (internally rotated)	30-45° inward	Outer hamstrings (biceps femoris)

Note: Effects are subtle. Use primarily for variety and addressing specific weaknesses.

By Tempo & Technique

Variation	Modification	Purpose	Difficulty
Pause reps	2-5 second hold at peak contraction	Enhanced activation, stability	⭐⭐
Slow eccentric	4-6 second lowering phase	Eccentric strength, control	⭐⭐⭐
1.5 reps	Full curl + half down + full curl = 1 rep	Time under tension	⭐⭐⭐
Constant tension	Don't fully extend, stay in partial ROM	Continuous muscle activation	⭐⭐
Isometric holds	Hold at various angles (90°, 45°)	Positional strength	⭐⭐
Drop sets	Reduce weight at failure, continue	Metabolic stress	⭐⭐⭐

Equipment Variations

Standing Curl Machine

Standard dedicated machine:

• Pad swings in arc behind you
• Support platform for standing leg
• Adjustable height and arm length

Pros: Purpose-built, stable, effective Cons: Not all gyms have this machine

Cable Standing Curl

Cable machine with ankle cuff:

• Attach ankle cuff to low cable
• Stand facing away from machine
• Curl against cable resistance

Pros: Available in more gyms, adjustable resistance angle Cons: Less stable, requires more balance

Link: Cable Leg Curl

Resistance Band

Band attached to anchor:

• Loop band around ankle
• Anchor band low behind you
• Curl against band resistance

Pros: Portable, home-friendly, joint-friendly resistance curve Cons: Less resistance available, harder to progressively overload

Advanced Challenges

Once you've mastered standard standing leg curls:

1. Eyes closed: Eliminates visual balance input — much harder
2. Unstable surface: Stand on balance pad/BOSU — functional training
3. Tempo extremes: 10-second eccentric for control mastery
4. Cluster sets: 3 reps, rest 10s, 3 reps, rest 10s, 3 reps = 1 set

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📊 Programming

Rep Ranges by Goal

Goal	Sets	Reps (Per Leg)	Rest	Tempo	RIR
Strength	3-4	8-12	90-120s	2-1-2-0	2-3
Hypertrophy	3-4	10-15	60-90s	2-2-3-0	1-2
Endurance	2-3	15-20+	45-60s	1-0-2-0	2-3
Balance/Stability	2-3	10-12	60-90s	2-2-3-1	3-4

Workout Placement

Program Type	Placement	Volume	Rationale
Leg day	After compounds, middle of workout	3-4 sets	Isolation after squats/deads
Pull day	Mid-workout	3 sets	Hamstrings with back work
Unilateral focus day	Primary or secondary	4 sets	When fixing imbalances
Full body	End of session	2-3 sets	Accessory work

Load Expectations

Weight comparison to bilateral variations:

If you can do:

• Lying leg curl bilateral: 100 lbs
• Standing curl single-leg: 40-50 lbs per leg (40-50% of bilateral)

Why the difference?

• Stability demands reduce max force output
• No help from opposite leg
• Balance component limits load

Don't compare standing to bilateral weights — they're different exercises!

Exercise Pairing Strategies

Unilateral supersets:

• Standing Leg Curl (right leg) → Standing Leg Curl (left leg) → Single-Leg RDL (alternating)

Bilateral/unilateral combo:

• Lying Leg Curl (both legs, heavy) → Standing Leg Curl (single-leg, lighter)

Antagonist pairing:

• Standing Leg Curl → Single-Leg Extension (hamstrings + quads, same leg)

Balance/stability circuit:

• Standing Leg Curl → Single-Leg RDL → Bulgarian Split Squat

Frequency Guidelines

Training Level	Frequency	Weekly Sets (Total Both Legs)
Beginner	1-2x/week	6-9 sets
Intermediate	2x/week	8-12 sets
Advanced	2x/week	10-16 sets

Note: Count total sets across both legs. 3 sets per leg = 6 total sets.

Progression Strategies

Progressive overload options:

1. Weight: Add 5 lbs when hitting top of rep range with good balance
2. Reps: Add 1-2 reps per set
3. Sets: Add 1 set per leg
4. Tempo: Slower eccentric (2s → 3s → 4s)
5. Stability: Remove visual input (eyes closed), unstable surface
6. Technique: Add pauses, isometric holds

Unilateral Progression Note

Progress each leg INDEPENDENTLY. If your right leg can do 12 reps but your left only gets 10, keep the weight the same until both legs can achieve the target. This is how you fix imbalances.

Sample Hamstring Programs Including Standing Curls

Program 1: Imbalance Correction Focus

1. Romanian Deadlift — 3x8 (bilateral strength)
2. Standing Leg Curl — 4x10-12/leg (identify and fix imbalance)
3. Single-Leg RDL — 3x8/leg (functional unilateral)

Program 2: Balanced Development

1. Lying Leg Curl — 4x10-12 (bilateral, heavier)
2. Standing Leg Curl — 3x12-15/leg (unilateral finisher)
3. Nordic Curl — 2x6-8 (eccentric emphasis)

Program 3: Functional/Athletic

1. Kettlebell Swing — 4x10 (explosive posterior chain)
2. Standing Leg Curl — 3x10/leg (isolated strength)
3. Single-Leg RDL — 3x8/leg (balance + hamstring)

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🔄 Alternatives & Progressions

Exercise Progression Path

Regressions (Easier)

Exercise	When to Use	Benefit	Link
Resistance Band Leg Curl	Very beginner, home training	Light, adjustable	✓
Slider Leg Curl (single-leg)	No machine, bodyweight	Builds base strength	✓
Cable Leg Curl	Want adjustable resistance	Versatile, available	✓

Progressions (Harder)

Exercise	When Ready	Challenge	Link
Single-Leg RDL	Master standing curl	Functional, compound movement	✓
Nordic Curl (single-leg)	Elite strength	Extreme eccentric, unilateral	✓
Glute-Ham Raise (single-leg)	Advanced unilateral work	Full posterior chain	✓

Alternatives (Different Equipment, Same Goal)

Machine Alternatives

Alternative	Position	Key Difference
Lying Leg Curl	Prone, bilateral	Better stretch, heavier loads
Seated Leg Curl	Seated, bilateral	Peak contraction, constant tension
Cable Leg Curl	Standing/kneeling	Adjustable angle, more gyms have it

When to choose:

• Heavy loads: Lying leg curl
• Peak contraction: Seated leg curl
• Unilateral isolation: Standing leg curl (what you're doing!)

Other Unilateral Options

Alternative	Type	Unique Benefit
Single-Leg Lying Curl	Isolation	Unilateral without balance challenge
Single-Leg RDL	Compound	Functional, full posterior chain
Cable Leg Curl (single-leg)	Isolation	More versatile resistance angle

Bodyweight Unilateral

Alternative	Equipment	Difficulty
Nordic Curl (single-leg)	Ankle anchor	Very advanced
Slider Curl (single-leg)	Slider	Intermediate
Swiss Ball Curl (single-leg)	Stability ball	Intermediate

Exercise Selection Guide

Choose Standing Leg Curl when:

• You need to identify/fix strength imbalances
• You want functional single-leg strength
• You want mind-muscle connection on each leg independently
• You're doing unilateral-focused training block

Choose Lying/Seated Leg Curl when:

• You want to lift heavy
• You're focused on pure muscle size
• Balance is fatiguing you before hamstrings are worked adequately
• You're a beginner building base strength

Choose compound unilateral (RDL, etc.) when:

• You want functional strength transfer to sports
• You need full posterior chain development
• Time is limited (more bang for buck)

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🛡️ Safety & Contraindications

Who Should Be Careful

Condition	Risk Level	Concern	Modification
Acute hamstring strain	🔴 High	Re-injury	AVOID until healed, cleared
Balance disorders	🟡 Moderate	Fall risk	Use bilateral variation instead
Ankle instability	🟡 Moderate	Support leg stability compromised	Strengthen ankle first, or use bilateral
Knee issues (support leg)	🟢 Low	Standing on one leg may aggravate	Monitor pain, reduce weight
Hamstring tendinopathy	🟡 Moderate	Insertion point irritation	Reduce ROM, lighter weight

Stop Immediately If

• Sharp pain in working hamstring
• Balance loss that risks falling
• Pain in support leg knee or ankle
• Popping or tearing sensation
• Severe cramping that won't release

Safety Considerations

Balance and fall risk:

• Always have stable machine or wall nearby to grab if needed
• Start with lighter weight than you think you need
• Don't train to absolute failure on standing exercises
• Clear area around you of obstacles

Support leg protection:

• Maintain slight knee bend (never lock)
• Distribute weight evenly through foot
• Don't stay on one leg for extended periods between sets
• Switch legs if support leg fatigues

Injury Prevention Benefits

Standing leg curls help prevent:

1. Bilateral strength imbalances — forces each leg to work independently
2. Functional weakness — builds single-leg strength for sports/life
3. Hamstring strains — eccentric strength reduces injury risk
4. Compensation patterns — can't hide weak side

Injury prevention protocol:

• Include unilateral hamstring work 1-2x per week
• Emphasize eccentric control (2-3+ second lowering)
• Monitor strength differences between legs (should be <10%)
• Progress gradually — don't rush

Common Issues & Solutions

Issue	Cause	Solution
Loss of balance mid-set	Too heavy, fatigue, or poor setup	Reduce weight, reset between reps
Support leg fatigue	Weak glute medius/stabilizers	Strengthen with Single-Leg RDL, lateral band walks
Cramping in working hamstring	Dehydration, too heavy	Hydrate, reduce weight, stretch
One leg much weaker	Normal imbalance	Keep weight same for both legs until balanced
Can't feel hamstring working	Balance stealing focus	Start with bilateral variation first

Safe Progression Guidelines

Week	Focus	Weight Progression
1-2	Learn balance, establish baseline	30-40% of bilateral weight
3-4	Improve stability	Add 5 lbs if stable
5-8	Build strength	Add 5 lbs every 1-2 weeks
9+	Progressive overload	Continue gradual progression

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🦴 Joints Involved

Joint	Primary Action	ROM Required	Stress Level	Leg
Knee (working)	Flexion/Extension	0-135° flexion	🟡 Moderate	Working
Hip (working)	Isometric stability	Maintained neutral	🟢 Low	Working
Knee (support)	Isometric flexion	~10-20° bend held	🟡 Moderate	Support
Hip (support)	Stabilization	Multiple planes	🟡 Moderate	Support
Ankle (support)	Stabilization	Small adjustments	🟡 Moderate	Support
Spine	Neutral stability	Maintained neutral	🟢 Low	Both

Mobility Requirements

Joint	Minimum ROM	Test	If Limited
Knee (working)	135° flexion	Can touch heel to butt	Reduce ROM
Hip	Neutral extension	Can stand upright	Usually not an issue
Ankle	10° dorsiflexion	Single-leg balance	May affect support leg stability

Unique Joint Demands

Standing position creates different demands than bilateral variations:

1. Support leg stabilization:

   • Hip abductors/adductors work to maintain alignment
   • Ankle stabilizers constantly adjust
   • Knee held in slight flexion (isometric quad work)

2. Working leg:

   • Isolated knee flexion/extension
   • Hip must remain stable (don't hike or drop)

3. Spine and core:

   • Prevent rotation
   • Maintain upright posture
   • Anti-lateral flexion (don't lean to side)

Functional benefit: These stability demands make standing curls more transferable to real-world movements and sports than bilateral machine variations.

Joint Health Considerations

Knees:

• Generally safe for knees
• Working leg: isolated flexion, no weight-bearing stress
• Support leg: slight bend reduces stress
• Don't lock support knee

Hips:

• Excellent for hip stabilizer strength
• Challenges frontal and transverse plane stability
• Builds functional single-leg strength

Ankles:

• Support ankle gets proprioceptive training
• Strengthens ankle stabilizers
• May be challenging for those with ankle instability

Spine:

• Minimal stress if upright posture maintained
• Core engagement protects spine
• Safer than bilateral variations for most people

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❓ Common Questions

How much weight should I use compared to lying or seated leg curls?

Start with 40-50% of your bilateral (both legs) leg curl weight.

Example:

• If you lying leg curl 100 lbs with both legs
• Start standing leg curl with 40-50 lbs per leg

Why so much less?

• Balance demands reduce max force output
• No assistance from opposite leg
• Stability muscles share the load
• Standing position is mechanically different

This is normal and expected. Don't compare them directly — they're different exercises with different challenges.

One leg is way stronger than the other — is this normal?

Small differences are normal; large differences need attention.

Normal: 5-10% strength difference between legs Notable: 10-20% difference — work on balancing Significant: 20%+ difference — prioritize correction

How to fix:

1. Use the weight your WEAK leg can handle for BOTH legs
2. Start with your weak leg first each set
3. Match reps on both sides (even if strong leg could do more)
4. Do one extra set on weak side if needed
5. Be patient — takes weeks/months to balance out

Don't: Use different weights for each leg during the same workout. Keep weight consistent, let weak side catch up naturally.

I keep losing my balance — what's wrong?

Common causes and fixes:

1. Too much weight — #1 reason

   • Fix: Reduce weight by 20-30%, focus on stability

2. Support knee locked

   • Fix: Maintain slight bend in support leg

3. Weak hip stabilizers

   • Fix: Add lateral band walks, single-leg RDLs to build stability

4. Poor foot position

   • Fix: Entire foot on platform, weight distributed evenly

5. Gripping handles too hard

   • Fix: Lighter grip, use for balance only, not pulling

6. Core not engaged

   • Fix: Brace core before each rep

If balance is consistently impossible: Start with bilateral variations (lying or seated) to build base hamstring strength, then return to standing curls later.

Should I do standing leg curls if my gym has lying and seated machines?

Yes, as part of a balanced program — here's why:

Advantages of standing curls:

• Identifies imbalances that bilateral exercises hide
• Develops single-leg functional strength
• Trains balance and stability
• Better transfer to sports and daily activities
• Challenges core and hip stabilizers

Suggested approach:

• Primary hamstring work: Lying or seated leg curl (heavier, bilateral)
• Supplementary work: Standing leg curl (unilateral, balance challenge)

Sample weekly split:

• Day 1: Lying Leg Curl 4x10-12 (both legs, heavy)
• Day 4: Standing Leg Curl 3x10/leg (unilateral, lighter)

Or: Rotate them — one week lying, next week standing, etc.

Can I do standing leg curls at home without a machine?

Yes! Several options:

1. Resistance band:

   • Anchor band low behind you
   • Loop around ankle
   • Stand and curl against band resistance
   • Cheapest option ($10-20)

2. Cable machine (if you have access):

   • Ankle cuff attachment
   • Low pulley position
   • Face away and curl

3. Bodyweight alternatives:

   • Slider leg curl (single-leg) — requires sliders or towels
   • Swiss ball leg curl (single-leg) — requires stability ball

Resistance bands are the best home option for replicating standing leg curls. They're portable, affordable, and effective.

How do I progress on standing leg curls?

Progression methods in order of preference:

1. Add reps: 8 → 10 → 12 (within your target range)
2. Add weight: Increase by 5 lbs when you hit top of rep range with good form
3. Improve tempo: Slower eccentric (2s → 3s → 4s)
4. Add sets: 3 sets → 4 sets per leg
5. Add stability challenge: Eyes closed, unstable surface, pause reps

Key principle for unilateral exercises:

• Progress BOTH legs together, based on your WEAK leg's performance
• Don't add weight just because your strong leg can handle it
• Let weak leg dictate progression — this is how imbalances get fixed

Timeline:

• Weeks 1-4: Focus on balance and form, small weight increases
• Weeks 5-12: Steady progression, add 5 lbs every 2-3 weeks
• Week 13+: Continue progressive overload, reassess imbalances

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📚 Sources

Biomechanics & Muscle Activation:

• Ebben, W.P. (2009). Hamstring Activation During Leg Curl Variations — Tier A
• McCurdy, K. et al. (2010). Unilateral vs Bilateral Exercise Muscle Activation — Tier A
• ExRx.net Exercise Analysis — Tier C

Unilateral Training:

• Gonzalo-Skok, O. et al. (2017). Single-Leg Strength Training for Athletic Performance — Tier A
• Bishop, C. et al. (2018). Bilateral Deficit: A Review — Tier A

Balance & Stability:

• Behm, D.G. et al. (2010). Instability Resistance Training — Tier A
• Anderson, K. et al. (2005). Core Stability During Single-Leg Exercise — Tier B

Injury Prevention:

• van der Horst, N. et al. (2015). Hamstring Injury Prevention Strategies — Tier A
• Croisier, J.L. et al. (2008). Strength Imbalances and Hamstring Injury Risk — Tier A

Programming:

• Schoenfeld, B.J. (2010). Mechanisms of Hypertrophy — Tier A
• Renaissance Periodization Guidelines — Tier B
• NSCA Exercise Technique Manual — Tier A

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For Mo

When to recommend this exercise:

• User wants to identify/fix strength imbalances between legs
• User needs functional single-leg hamstring strength
• User is athlete requiring balance and stability
• User's gym has standing leg curl machine
• User has noticed one leg is weaker and wants to address it
• User wants variety from bilateral leg curls
• User is doing unilateral-focused training block

Who should NOT do this exercise:

• Acute hamstring injury → Wait for healing and clearance
• Severe balance disorders → Use bilateral variations (lying, seated)
• Extreme ankle instability → Strengthen ankle first, or bilateral variation
• No access to machine AND no bands → Use bilateral or bodyweight alternatives

Key coaching cues to emphasize:

1. "Stay stable — don't rock or sway"
2. "Heel to glute — full contraction"
3. "Support leg has soft knee, not locked"
4. "Control the negative — 2-3 seconds"
5. "If you're losing balance, reduce the weight"

Common issues to watch for in user feedback:

• "I keep losing my balance" → Weight too heavy, need lighter load and stability focus
• "One leg is way stronger" → Normal to identify imbalances; use weak leg's capacity for both
• "I can't use as much weight as lying curls" → Expected! Standing = 40-50% of bilateral
• "My support leg gets tired" → Normal; builds functional strength; take breaks between legs
• "Should I do standing or lying?" → Both have benefits; include both if possible, or rotate

Programming guidance:

• Pair with: Other unilateral exercises (Single-Leg RDL, Bulgarian Split Squat)
• Avoid before: Heavy bilateral lifts (squats, deadlifts)
• Typical frequency: 1-2x per week
• Volume: 3-4 sets of 10-15 reps per leg
• Load: 40-50% of bilateral leg curl weight
• Placement: After compound lifts, mid-to-late in workout

Progression signals:

• Ready to add weight: Completing all reps both legs, RIR 2-3, stable balance
• Ready for advanced variations: Mastering standard version with excellent control
• Need to regress: Consistent balance loss, form breakdown, one leg doing all the work

Special notes:

• Standing leg curl is EXCELLENT for identifying imbalances that bilateral exercises hide
• Expect 5-15% difference between legs — this is valuable diagnostic information
• Balance component makes this more "functional" than lying/seated variations
• Can't load as heavy, but that's the tradeoff for unilateral work
• Great for athletes who need single-leg strength (running, jumping, cutting sports)
• Often overlooked in favor of bilateral variations, but very valuable for complete development

Imbalance assessment:

• 5-10% difference = normal, monitor
• 10-20% difference = notable, prioritize fixing
• 20%+ difference = significant, needs focused attention

Fixing imbalances:

1. Use weight weak leg can handle for BOTH legs
2. Start with weak leg first each set
3. Match reps on both sides
4. Optional: 1 extra set on weak side
5. Reassess every 4 weeks

Equipment alternatives:

• No machine? → Resistance band leg curl (home option)
• Want adjustable angle? → Cable leg curl
• Need bilateral? → Lying or Seated

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Last updated: December 2024