After analyzing Olas's social feed implementation, I can provide you with valuable insights for building your workout-focused social feed using Nostr. Here's a breakdown of their implementation and how you can adapt it for POWR:

### Key Components of Olas's Feed Implementation

1. **Feed Architecture**
- They use a main `Feed` component with two key parts:
  - `useFeedEvents` hook for managing feed data
  - `useFeedMonitor` hook for monitoring and updating feed entries

2. **NDK Integration**
```typescript
import { 
    NDKEvent, 
    NDKFilter, 
    NDKKind, 
    NDKSubscription,
    useNDK 
} from "@nostr-dev-kit/ndk-mobile";
```

3. **Event Filtering**
- They filter events based on specific kinds:
```typescript
switch (event.kind) {
    case NDKKind.VerticalVideo:
    case NDKKind.HorizontalVideo:
    case 30018:
    case 30402:
    case NDKKind.Text:
    case NDKKind.Media:
    case NDKKind.Image: 
        return handleContentEvent(eventId, event);
```

### Implementing POWR's Workout Feed

For your workout app, here's how you can adapt their implementation:

1. **Event Kind Definition**
```typescript
// Define workout event kind
const WORKOUT_EVENT_KIND = 30311; // Choose an appropriate kind number for workouts
```

2. **Feed Filter Setup**
```typescript
const workoutFeedFilters: NDKFilter[] = [{
    kinds: [WORKOUT_EVENT_KIND],
    // Add any additional filters like tags
}];
```

3. **Feed Component**
```typescript
import { NDKEvent, NDKFilter, useNDK } from "@nostr-dev-kit/ndk-mobile";

export function WorkoutFeed() {
    const { entries, newEntries, updateEntries } = useFeedEvents(
        workoutFeedFilters,
        { 
            subId: 'workout-feed',
            filterFn: (entry) => {
                // Add custom filtering for workout events
                return true;
            }
        }
    );

    return (
        <FlashList
            data={entries}
            renderItem={({ item }) => (
                <WorkoutPost 
                    event={item.event}
                    timestamp={item.timestamp}
                />
            )}
            estimatedItemSize={400}
        />
    );
}
```

4. **Useful NDK Tools to Leverage**
- **Subscription Management**
```typescript
const subscription = ndk.subscribe(
    workoutFeedFilters,
    { 
        groupable: false,
        skipVerification: true,
        subId: 'workout-feed'
    }
);

subscription.on("event", handleWorkoutEvent);
subscription.once('eose', handleEose);
```

- **Event Processing**
```typescript
const handleWorkoutEvent = (event: NDKEvent) => {
    // Process workout specific data
    const workout = {
        id: event.id,
        type: event.tagValue('workout-type'),
        duration: event.tagValue('duration'),
        // other workout specific fields
    };
    
    // Update feed
    updateEntry(event.id, (entry) => ({
        ...entry,
        event,
        workout,
        timestamp: event.created_at
    }));
};
```

5. **Feed Entry Type**
```typescript
type WorkoutFeedEntry = {
    id: string;
    event?: NDKEvent;
    workout?: {
        type: string;
        duration: string;
        // other workout metadata
    };
    timestamp: number;
};
```

### Key NDK Tools to Use

1. **Event Subscription**
- `NDKSubscription` for real-time workout updates
- `NDKFilter` for filtering workout-specific events

2. **Event Processing**
- `NDKEvent` for handling workout event data
- Event tags for workout metadata

3. **Feed Management**
- `useFeedEvents` hook pattern for managing workout feed state
- Entry caching and update mechanisms

### Best Practices from Olas's Implementation

1. **Performance Optimization**
- Use of `FlashList` for efficient list rendering
- Implement entry caching
- Handle new entries efficiently

2. **State Management**
- Track active entries
- Manage subscription lifecycle
- Handle feed updates appropriately

3. **User Experience**
- Implement pull-to-refresh
- Show new entries notification
- Handle scrolling and viewing positions

### Additional Recommendations for POWR

1. **Workout-Specific Filters**
- Add filters for workout types
- Filter by duration, intensity, etc.
- Use workout-specific tags

2. **Data Structure**
```typescript
// Workout event structure
const workoutEvent = {
    kind: WORKOUT_EVENT_KIND,
    tags: [
        ['workout-type', 'strength'],
        ['duration', '45'],
        ['exercises', JSON.stringify(exercises)],
        // Additional metadata
    ],
    content: workoutDescription
};
```

3. **Real-time Updates**
- Implement real-time workout progress updates
- Show active workouts in progress
- Enable social interactions during workouts

This implementation will give you a solid foundation for building a workout-focused social feed using Nostr. The key is adapting Olas's efficient feed management system while customizing it for workout-specific content and interactions.