Why is my forearm heavy and my motor strength weak, especially after using a sling, despite being able to lift 10 pounds?

Forearm Heaviness and Motor Weakness After Sling Use

Your symptoms of forearm heaviness and motor weakness after using a sling indicate incomplete nerve recovery that requires immediate discontinuation of the sling and initiation of structured rehabilitation with functional electrical stimulation and resistance training. 1, 2

Why the Sling Is Causing Your Symptoms

The sling is worsening your condition through multiple mechanisms:

• Prolonged immobilization causes rapid muscle deconditioning, with strength loss most dramatic during the first week of immobilization 2
• Static positioning promotes "learned non-use" where your brain stops attempting to use the affected limb, worsening functional outcomes 2, 3
• Slings can exacerbate symptoms by maintaining the wrist and forearm in end-range positions that impede recovery 1, 2
• Research shows that arm slings may actually inhibit active correction of motor deficits rather than supporting recovery 4

Critical Action: Stop Using the Sling

Guidelines explicitly advise against splinting in the recovery phase for nerve injuries with partial motor return: 1

• The American Academy of Physical Medicine and Rehabilitation recommends avoiding static immobilization as it causes muscle deconditioning and can trigger complex regional pain syndrome 2
• Your ability to lift 10 pounds demonstrates you have partial motor function, which is the exact population that should NOT be immobilized 1, 5

Your Recovery Prognosis

You will heal, but only with appropriate rehabilitation:

• Resolution of wrist drop (which you've achieved) indicates significant motor recovery has already occurred, which is a positive prognostic indicator 1
• The persistent motor weakness represents incomplete recovery that will NOT spontaneously improve without structured intervention 1, 2
• Most motor recovery gains occur within the first 6 months, making this a critical window for intensive rehabilitation 2
• Expected timeline: rapid symptom relief typically occurs within 3-4 months with appropriate rehabilitation, with optimal functional recovery requiring 9-12 months 1, 2

Required Treatment Protocol

Functional Electrical Stimulation (Primary Intervention)

FES is specifically indicated for your condition:

• Apply functional electrical stimulation to wrist and forearm extensor muscles as an adjunct to task-specific training 1, 5, 2
• FES promotes neural reorganization by providing sensory input and facilitating more complete muscle contractions, increasing proprioceptive feedback that promotes motor learning 5
• Strong evidence supports efficacy for individuals less than 6 months post-injury, with improved outcomes when combined with regular therapy 5
• FES provides short-term increases in motor strength and control specifically for patients with impaired muscle contraction and wrist motor impairment 5

Task-Specific Practice

Intensive functional training is essential:

• Perform task-specific training focusing on wrist extension and flexion movements with progressive difficulty 1, 2
• Progress from supported (table-based) to unsupported wrist movements as motor control improves 1, 2
• Incorporate activities requiring normal movement patterns with proper alignment during functional tasks 1, 2
• Use the affected hand to stabilize objects during bilateral tasks 2

Resistance Training Protocol

Follow this specific progression:

• Begin with low-intensity resistance at 40% of 1-repetition maximum with 10-15 repetitions 1, 2
• Progress to moderate intensity (41-60% of 1-RM) with 8-10 repetitions as tolerated 1
• Perform resistance training 2-3 times per week to allow adequate recovery between sessions 1, 2
• Implement static stretches held for 10-30 seconds with 3-4 repetitions for each stretch 1, 2
• Critical warning: Do not progress resistance too quickly—start with very low intensity during initial sessions to avoid muscle damage 1, 2

Dynamic Splinting (If Support Needed)

Only use dynamic support, never static:

• If support is absolutely necessary, use dynamic splinting that provides wrist and finger extension support through a tenodesis mechanism while allowing movement 2
• Avoid serial casting or prolonged static immobilization 2
• Reassess splint effectiveness every 2-3 weeks to adjust therapy progression 2

What NOT to Do

These interventions will harm your recovery:

• Do not rely on passive range of motion alone—active motor practice is essential 1, 2
• Avoid prolonged positioning of the wrist at end ranges, which exacerbates symptoms and impedes recovery 1, 2
• Never completely immobilize the limb 2
• Do not use vibration devices—insufficient evidence exists to recommend them, and they may promote compensatory strategies that worsen outcomes 2

Treatment Frequency and Duration

• Perform rehabilitation 2-3 times per week for flexibility and resistance training 1, 2
• Continue intensive rehabilitation for 9-12 months depending on functional goals 1, 2
• The first 6 months represent the critical window for maximum recovery 2