- t1 = First intervention session post-allocation, t2 = week 6, t3 = week 12, t4 = week 26. SPA Sub-threshold Physical Activity, SPSS Post-Concussion Symptoms Scale, NPRS Numerical Pain Rating Scale, NDI Neck Disability Index, DHI Dizziness Handicap Inventory, HDI Headache Disability Index, GRC global rating of change