PPCSexRx encodes sub-symptom threshold aerobic exercise (SSTAE) algorithms developed from a systematic review recognised with the 2026 NATA Foundation Best Summary Evidence Research Award (Li, 2026). The peer-reviewed evidence synthesis and CAT logic are archived at OSF (doi:[10.17605/osf.io/kvuf6](https://doi.org/10.17605/osf.io/kvuf6)).
The package is intentionally framed as a clinical decision support system (CDSS), not a black-box calculator: it translates GRADE-rated evidence into executable screening, prescribing, and progress-tracking rules while surfacing certainty, citations, and explicit safety stops at every tier of resource availability.
The intended workflow mirrors bedside practice:
screen_ppcs() --> prescribe_ppcs() --> track_progress()GRADE disclosure: SSTAE recommendations encoded here carry LOW certainty evidence with a conditional recommendation FOR use in adolescents meeting PPCS definitions (Li, 2026). Licensed clinicians remain accountable for all treatment decisions.
A 16-year-old athlete presents 35 days after concussion with persistent symptoms consistent with PPCS. Your clinic completed a Buffalo Concussion Treadmill Test (BCTT); symptom-threshold heart rate (HRst) was 145 bpm. There are no active vestibular or cervical contraindications.
This vignette section demonstrates scientific
fidelity: when objective exertional testing exists,
prescribe_ppcs() prefers 80% of HRst as
the prescription anchor (Li, 2026, p.11).
screen_ppcs(
age = 16,
days_post_injury = 35,
vestibular_symptoms = FALSE,
cervical_symptoms = FALSE
)
#> ========================================
#> PPCSexRx Eligibility Screen
#> GRADE: LOW certainty | Li (2026)
#> ========================================
#> [OK] STATUS: ELIGIBLE
#>
#> CLINICAL REASON:
#> Patient meets PICO eligibility criteria: age 16 years, 35 days post-injury (>= 28), no active contraindications. Proceed to BCTT-guided prescription (Li, 2026).
#>
#> NEXT STEP:
#> Proceed to prescribe_ppcs(). BCTT preferred for HR target; age-predicted fallback if unavailable.
#> ========================================
#> For prescription: prescribe_ppcs()
#> Evidence: Li G. (2026). NATA Foundation Award.
#> ========================================rx_gold <- prescribe_ppcs(
age = 16,
days_post_injury = 35,
hrst = 145,
vestibular_symptoms = FALSE,
cervical_symptoms = FALSE
)
rx_gold
#> ========================================
#> PPCSexRx Clinical Prescription
#> Evidence-Based Protocol | Li (2026)
#> ========================================
#> Target HR : 116 bpm
#> Duration : 20 min/session
#> Frequency : 5 sessions/week
#> Method : BCTT-guided: 80% of symptom threshold HR
#> ----------------------------------------
#> CLINICAL NOTE : Maintain current intensity. Monitor weekly for tolerance.
#> SAFETY : Clinician supervision required. Stop if symptoms worsen >= 2 PCSS points. See Li (2026), p.14.
#> EVIDENCE : GRADE: LOW certainty. Conditional recommendation FOR. See Li (2026), p.11.
#> ========================================The computed target HR implements 116 bpm (= 80% x 145
bpm) together with structured disclosures (method,
evidence_grade, safety_warning) so auditors
can trace every numeric output back to protocol
language.
A 14-year-old student-athlete is seen at a remote high school without treadmill testing capability 20 days post-injury. Even though HR monitors might be available, the athlete does not yet meet PPCS chronology (fewer than 28 days post-injury are handled outside this SSTAE pathway).
This section demonstrates operational safety: the
package refuses to mint an SSTAE prescription when core eligibility
gates fail, regardless of whether hrst is omitted (resource
fallback path).
screen_ppcs(
age = 14,
days_post_injury = 20,
vestibular_symptoms = FALSE,
cervical_symptoms = FALSE
)
#> ========================================
#> PPCSexRx Eligibility Screen
#> GRADE: LOW certainty | Li (2026)
#> ========================================
#> [STOP] STATUS: CONTRAINDICATED
#>
#> CLINICAL REASON:
#> Symptoms present for only 20 days. PPCS requires >= 28 days post-injury (Li, 2026, p.2). SSTAE is not indicated at this stage.
#>
#> NEXT STEP:
#> Re-screen when >= 28 days post-injury. Continue standard concussion management.
#> ========================================
#> For prescription: prescribe_ppcs()
#> Evidence: Li G. (2026). NATA Foundation Award.
#> ========================================prescribe_ppcs()Attempting to prescribe without satisfying PPCS timing triggers an immediate error—there is no silent downgrade to age-based intensities.
prescribe_ppcs(
age = 14,
days_post_injury = 20,
vestibular_symptoms = FALSE,
cervical_symptoms = FALSE
)
#> Error in `prescribe_ppcs()`:
#> ! Contraindicated: PPCS defined as >=28 days post-injury. See Li (2026), p.2.Expected safeguard text includes
Contraindicated: PPCS defined as >=28 days post-injury.,
reinforcing that advanced arithmetic never substitutes for
foundational eligibility checks.
Together, Case Studies 1 and 2 convey the design thesis demanded by tertiary clinics and resource-constrained outreach programmes: precision where physiology is measured, deterministic refusal where physiology must not yet be stressed.
screen_ppcs() captures referrals for
vestibular, cervical, age-out-of-evidence, or vision-risk contexts
before exertional planning advances.track_progress() operationalises
session-by-session PCSS deltas with HR titration tied to Li (2026), p.14
progression/stop logic.Always pair package outputs with local policies, concussion RTP statutes, and supervising physician judgement.
Key caveats from the underlying CAT:
Li G. (2026). Sub-symptom Threshold Aerobic Exercise for Adolescents With Persistent Post-concussion Symptoms (PPCS): A Critically Appraised Topic. Winner, NATA Foundation Best Summary Evidence Research Award. https://doi.org/10.17605/osf.io/kvuf6
Leddy JJ, Haider MN, Ellis MJ, et al. Early Subthreshold Aerobic Exercise for Sport-Related Concussion. JAMA Pediatr. 2019;173(4):319–325.
Kurowski BG, et al. Aerobic Exercise for Adolescents With Prolonged Symptoms After Mild Traumatic Brain Injury. J Head Trauma Rehabil. 2017;32(2):79–89.
Vernau BT, Haider MN, Fleming A, et al. Exercise-Induced Vision Dysfunction Early After Sport-Related Concussion Is Associated With Persistent Postconcussive Symptoms. Clin J Sport Med. 2023;33(4):388–394.