diff --git a/src/lib/storage/workoutStorage.ts b/src/lib/storage/workoutStorage.ts
new file mode 100644
index 0000000..a1d69d8
--- /dev/null
+++ b/src/lib/storage/workoutStorage.ts
@@ -0,0 +1,185 @@
+// Workout and metrics persistence layer
+
+interface WorkoutSession {
+  id: string;
+  type: 'cardio' | 'training' | 'nutrition';
+  date: string;
+  data: Record<string, any>;
+  createdAt: number;
+}
+
+interface UserMetrics {
+  totalWorkouts: number;
+  totalDistance: number;
+  totalCalories: number;
+  totalWeight: number;
+  consistency: number; // days in a row
+  lastUpdated: number;
+}
+
+const STORAGE_KEYS = {
+  WORKOUTS: 'fitflow_workouts',
+  METRICS: 'fitflow_metrics',
+  USER_PROFILE: 'fitflow_user_profile',
+} as const;
+
+export class WorkoutStorageService {
+  // Workout Session Management
+  static saveWorkoutSession(session: Omit<WorkoutSession, 'id' | 'createdAt'>): WorkoutSession {
+    try {
+      const sessions = this.getWorkoutSessions();
+      const newSession: WorkoutSession = {
+        id: `workout_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`,
+        ...session,
+        createdAt: Date.now(),
+      };
+      sessions.push(newSession);
+      localStorage.setItem(STORAGE_KEYS.WORKOUTS, JSON.stringify(sessions));
+      return newSession;
+    } catch (error) {
+      console.error('Error saving workout session:', error);
+      throw error;
+    }
+  }
+
+  static getWorkoutSessions(): WorkoutSession[] {
+    try {
+      const data = localStorage.getItem(STORAGE_KEYS.WORKOUTS);
+      return data ? JSON.parse(data) : [];
+    } catch (error) {
+      console.error('Error retrieving workout sessions:', error);
+      return [];
+    }
+  }
+
+  static getWorkoutSessionsByType(type: WorkoutSession['type']): WorkoutSession[] {
+    const sessions = this.getWorkoutSessions();
+    return sessions.filter(session => session.type === type);
+  }
+
+  static getWorkoutSessionsByDate(date: string): WorkoutSession[] {
+    const sessions = this.getWorkoutSessions();
+    return sessions.filter(session => session.date === date);
+  }
+
+  static updateWorkoutSession(id: string, updates: Partial<WorkoutSession>): WorkoutSession | null {
+    try {
+      const sessions = this.getWorkoutSessions();
+      const index = sessions.findIndex(s => s.id === id);
+      if (index === -1) return null;
+      
+      const updated = { ...sessions[index], ...updates, id: sessions[index].id, createdAt: sessions[index].createdAt };
+      sessions[index] = updated;
+      localStorage.setItem(STORAGE_KEYS.WORKOUTS, JSON.stringify(sessions));
+      return updated;
+    } catch (error) {
+      console.error('Error updating workout session:', error);
+      return null;
+    }
+  }
+
+  static deleteWorkoutSession(id: string): boolean {
+    try {
+      const sessions = this.getWorkoutSessions();
+      const filtered = sessions.filter(s => s.id !== id);
+      localStorage.setItem(STORAGE_KEYS.WORKOUTS, JSON.stringify(filtered));
+      return filtered.length < sessions.length;
+    } catch (error) {
+      console.error('Error deleting workout session:', error);
+      return false;
+    }
+  }
+
+  // Metrics Management
+  static saveMetrics(metrics: UserMetrics): void {
+    try {
+      localStorage.setItem(STORAGE_KEYS.METRICS, JSON.stringify(metrics));
+    } catch (error) {
+      console.error('Error saving metrics:', error);
+    }
+  }
+
+  static getMetrics(): UserMetrics {
+    try {
+      const data = localStorage.getItem(STORAGE_KEYS.METRICS);
+      if (!data) {
+        return {
+          totalWorkouts: 0,
+          totalDistance: 0,
+          totalCalories: 0,
+          totalWeight: 0,
+          consistency: 0,
+          lastUpdated: Date.now(),
+        };
+      }
+      return JSON.parse(data);
+    } catch (error) {
+      console.error('Error retrieving metrics:', error);
+      return {
+        totalWorkouts: 0,
+        totalDistance: 0,
+        totalCalories: 0,
+        totalWeight: 0,
+        consistency: 0,
+        lastUpdated: Date.now(),
+      };
+    }
+  }
+
+  static updateMetrics(updates: Partial<UserMetrics>): UserMetrics {
+    const current = this.getMetrics();
+    const updated: UserMetrics = { ...current, ...updates, lastUpdated: Date.now() };
+    this.saveMetrics(updated);
+    return updated;
+  }
+
+  // Calculated Metrics
+  static calculateMetricsFromSessions(): UserMetrics {
+    const sessions = this.getWorkoutSessions();
+    let totalDistance = 0;
+    let totalCalories = 0;
+    let totalWeight = 0;
+
+    sessions.forEach(session => {
+      if (session.data.distance) totalDistance += Number(session.data.distance) || 0;
+      if (session.data.calories) totalCalories += Number(session.data.calories) || 0;
+      if (session.data.weight) totalWeight += Number(session.data.weight) || 0;
+    });
+
+    return this.updateMetrics({
+      totalWorkouts: sessions.length,
+      totalDistance,
+      totalCalories,
+      totalWeight,
+    });
+  }
+
+  // Batch Operations
+  static clearAllData(): void {
+    try {
+      localStorage.removeItem(STORAGE_KEYS.WORKOUTS);
+      localStorage.removeItem(STORAGE_KEYS.METRICS);
+      localStorage.removeItem(STORAGE_KEYS.USER_PROFILE);
+    } catch (error) {
+      console.error('Error clearing data:', error);
+    }
+  }
+
+  static exportData(): { workouts: WorkoutSession[]; metrics: UserMetrics } {
+    return {
+      workouts: this.getWorkoutSessions(),
+      metrics: this.getMetrics(),
+    };
+  }
+
+  static importData(data: { workouts: WorkoutSession[]; metrics: UserMetrics }): void {
+    try {
+      localStorage.setItem(STORAGE_KEYS.WORKOUTS, JSON.stringify(data.workouts));
+      this.saveMetrics(data.metrics);
+    } catch (error) {
+      console.error('Error importing data:', error);
+    }
+  }
+}
+
+export type { WorkoutSession, UserMetrics };
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