diff --git a/ios/App/CoachWatch/WorkoutManager.swift b/ios/App/CoachWatch/WorkoutManager.swift
index 13c5a03..029f1bf 100644
--- a/ios/App/CoachWatch/WorkoutManager.swift
+++ b/ios/App/CoachWatch/WorkoutManager.swift
@@ -26,6 +26,7 @@ final class WorkoutManager: NSObject, ObservableObject {
 
     func startWorkout(activityType: HKWorkoutActivityType,
                       locationType: HKWorkoutSessionLocationType) async {
+        guard !isRunning, session == nil else { return }
         guard HKHealthStore.isHealthDataAvailable() else {
             statusMessage = "HealthKit indisponible sur cet appareil"
             return
@@ -63,6 +64,8 @@ final class WorkoutManager: NSObject, ObservableObject {
             isRunning = true
             statusMessage = nil
         } catch {
+            self.session = nil
+            self.builder = nil
             statusMessage = "Démarrage séance impossible : \(error.localizedDescription)"
         }
     }
@@ -141,7 +144,11 @@ extension WorkoutManager: HKWorkoutSessionDelegate {
             try? await builder.endCollection(at: date)
             _ = try? await builder.finishWorkout()
         }
-        Task { @MainActor in self.isRunning = false }
+        Task { @MainActor in
+            self.isRunning = false
+            self.session = nil
+            self.builder = nil
+        }
     }
 
     nonisolated func workoutSession(_ workoutSession: HKWorkoutSession,
@@ -150,6 +157,8 @@ extension WorkoutManager: HKWorkoutSessionDelegate {
         Task { @MainActor in
             self.statusMessage = "Erreur séance : \(message)"
             self.isRunning = false
+            self.session = nil
+            self.builder = nil
         }
     }
 }